How many hours is JST ahead of IST?

JST is currently +3h 30m relative to IST, using Asia/Kolkata and Asia/Tokyo as the live reference zones on this page.

What is the best workday overlap between IST and JST?

The current 9-to-5 overlap is about 4.5 hours: IST 9:00 AM previous day to 1:30 PM previous day, which matches JST 12:30 PM previous day to 5:00 PM previous day.

Which cities commonly use IST and JST?

IST commonly covers cities such as Mumbai, Delhi, Bengaluru, and Hyderabad, while JST commonly covers cities such as Tokyo, Yokohama, Osaka, and Nagoya.

Should I use IST/JST or exact IANA zones?

Use the abbreviations for a quick read, but use exact IANA zones such as Asia/Kolkata and Asia/Tokyo when you need something precise in software, travel plans, or long-range scheduling.

Timezone converter

IST to JST Converter.

IST → JSTGap: +3h 30m4.5h 9-5 overlap

IST to JST currently uses India Time in Asia/Kolkata and Japan Time in Asia/Tokyo as the live reference pair, with a +3h 30m live gap. IST and JST connects India and Japan, separated by 3.5 hours. This conversion shows up in manufacturing calls, automotive supply chains, and the late-morning India to early-afternoon Japan window where both teams are simultaneously productive.

Last updated recently. Offset math, DST behavior, and city coverage on both sides are refreshed from the live timezone dataset during the page revalidation window.

Ambiguity note

IST is ambiguous in this dataset, so the live converter uses Asia/Kolkata as the busiest reference zone while the city list below shows the wider label family.

From

IST

India Time

Asia/Kolkata · GMT+5:30 +05:30

--:--:--

Major markets in this grouping include Mumbai, Delhi, Bengaluru, Hyderabad.

JST

Japan Time

Asia/Tokyo · GMT+9 +09:00

--:--:--

Major markets in this grouping include Tokyo, Yokohama, Osaka, Nagoya.

Scheduling snapshot

Current gap

+3h 30m

IST +05:30 vs JST +09:00

9-to-5 overlap

4.5h

IST 9:00 AM previous day to 1:30 PM previous day

Representative countries

India, Israel, and Sri Lanka / Japan

Based on the busiest city and zone usage found in the current dataset.

Pair context

IST (Mumbai, +05:30) to JST (Tokyo, +09:00) is currently a +3h 30m conversion. Live coverage on the IST side is anchored by Mumbai, Delhi, Bengaluru, and Hyderabad; the JST side draws from Tokyo, Yokohama, Osaka, and Nagoya.

IST and JST connects India and Japan, separated by 3.5 hours. This conversion shows up in manufacturing calls, automotive supply chains, and the late-morning India to early-afternoon Japan window where both teams are simultaneously productive.

Both reference zones sit inside Asia, so this is a regional comparison rather than a long-haul conversion. The gap of +3h 30m mostly affects intra-continental travel, regional logistics, and Asia-wide calendars.

Neither IST nor JST observes daylight saving on the reference zones used here, so the gap stays steady all year. That makes this pair predictable for recurring meetings, broadcast schedules, and contracts that care about a stable offset.

IST and JST sit 3h 30m apart, leaving a generous 4.5h of shared 9-to-5 time. With that much overlap, this pair behaves almost like a single workday, so meeting times are negotiable rather than forced into a narrow corner of the calendar.

Pair details

Reference zone, current offsets, country and city anchors, overlap math, and date-shift answers for IST to JST.

Reference pair

Asia/Kolkata -> Asia/Tokyo

Live offsets

IST +05:30 vs JST +09:00

Meaning split

India Time / Japan Time

Country anchors

India, Israel, and Sri Lanka -> Japan

City anchors

Mumbai, Delhi, Bengaluru, Hyderabad -> Tokyo, Yokohama, Osaka, Nagoya

Workday overlap

4.5h window: IST 9:00 AM previous day-1:30 PM previous day

Morning answer

9 AM IST = 12:30 PM JST, same day

Evening answer

6 PM IST = 9:30 PM JST, same day

Calendar and scheduling context

Same-offset labels can share the same hour while still landing in different countries, calendars, cities, and workday windows. These notes show the practical context behind this conversion.

Exact pair identity

IST to JST is pinned to Asia/Kolkata -> Asia/Tokyo, with the shorthand labels shown as context. The city anchors are Mumbai, Delhi, Bengaluru, Hyderabad on the IST side and Tokyo, Yokohama, Osaka, Nagoya on the JST side, with +3h 30m between the live reference zones.

Civil calendar differences

The 12 popular-hour answers include 11 same-day conversions, 1 next-day conversions, and 0 previous-day conversions. That distribution is what separates this page from a static offset chart.

Same-offset caution

Nearby labels sharing a current offset include GMT+9 (To side), KST (To side), PWT (To side), WIT (To side), YAKT (To side). They may match mathematically, but their country calendars, city anchors, and common search intent differ from this exact pair.

Jurisdiction evidence

IST: India (IN); 3776 mapped cities; capital New Delhi; English, Hindi, Tamil; INR Indian rupee | IST: Israel (IL); 108 mapped cities; capital Jerusalem; Arabic, Hebrew; ILS Israeli new shekel | IST: Sri Lanka (LK); 60 mapped cities; capital Sri Jayawardenepura Kotte; Sinhala, Tamil; LKR Sri Lankan rupee | JST: Japan (JP); 1296 mapped cities; capital Tokyo; Japanese; JPY Japanese yen

Pair fingerprint

Offset behavior, DST gap changes, local calendar evidence, and the day-shift pattern across the most common conversion hours.

Offset behavior class

IST/JST is a regional or transcontinental offset gap: Asia/Kolkata currently reads +05:30, Asia/Tokyo reads +09:00, and the live delta is +3h 30m. This class decides whether the page behaves like a same-day planner or a handoff planner.

DST asymmetry check

Asia/Kolkata and Asia/Tokyo do not show a detected near-term DST gap-change note in this sample, but the page still exposes exact IANA zones so users do not treat the abbreviation pair as permanently fixed.

Calendar evidence

No country holiday snapshot is attached to this exact pair yet, so the page leans on city anchors, IANA zones, offsets, and the live conversion table instead of pretending a local calendar exists.

Day-shift fingerprint

Across the 12 popular-hour answers, this pair has 11 same-day answers, 1 next-day answers, 0 previous-day answers. That mix is specific to the current Asia/Kolkata -> Asia/Tokyo relationship and helps users see whether dates must be written explicitly in invites, travel plans, and release schedules.

Same-offset and canonical audit

Same-offset converter clusters can look identical if the page only shows a numeric offset. This audit states whether the route should be indexed, which canonical peer it follows when consolidated, and what pair-specific evidence keeps the page useful.

Indexing posture

This pair remains indexable because the route has enough pair-specific context: Asia/Kolkata -> Asia/Tokyo, country anchors, city anchors, calendar notes, and day-shift examples.

Same-offset math check

IST and JST are not currently a same-offset pair; the live delta is +3h 30m. Same-offset neighbors are still listed because users often confuse nearby abbreviations.

Neighbor audit

GMT+9 (To side, +09:00), KST (To side, +09:00), PWT (To side, +09:00), WIT (To side, +09:00), YAKT (To side, +09:00) The page keeps these labels visible so SGT/HKT/GST-style clusters do not blur into one generic offset page.

Canonical evidence

IST/JST uses 11 same-day answers, 1 next-day answers, 0 previous-day answers; 4.5h strict workday overlap; source zones Asia/Kolkata and Asia/Tokyo; country anchors India, Israel, and Sri Lanka -> Japan.

Local intent behind each abbreviation

Common places, calendars, markets, languages, and operating contexts behindIST and JST.

JST

JST local intent 1

JST is Japan civil time, centered on Tokyo, Yokohama, Osaka, Nagoya, Sapporo, Fukuoka, and the rest of the Japanese domestic timetable. The useful context is Japan's no-DST posture, yen-denominated business cycles, Tokyo Stock Exchange timing, rail and aviation punctuality, anime/game/media release schedules, and holiday clusters such as Golden Week and year-end closures.

JST

JST local intent 2

A JST conversion is often searched by teams coordinating with Japan specifically, not merely UTC+9. Product launches, live streams, travel arrivals, and support handoffs should account for Japanese business etiquette, local public holidays, and the difference between Japan's stable clock and regions where daylight saving changes the counterpart offset.

Country calendar contrast

Same-offset conversions can still land in different public-holiday, language, currency, and city-anchor contexts. These rows use the country profile and holiday snapshots behind each side of the pair.

IST

India

3,776 mapped city anchors; zones Asia/Kolkata.capital New Delhi; English, Hindi, Tamil; INR Indian rupee

Holiday snapshot: Republic Day (Jan 26, Public) · Holi (Mar 4, Public) · Eid al-Fitr (Mar 21, Public) · Mahavir Jayanti (Mar 31, Public) · Good Friday (Apr 3, Public)

IST

Israel

108 mapped city anchors; zones Asia/Jerusalem.capital Jerusalem; Arabic, Hebrew; ILS Israeli new shekel

Holiday snapshot: No holiday snapshot attached for the current year.

IST

Sri Lanka

60 mapped city anchors; zones Asia/Colombo.capital Sri Jayawardenepura Kotte; Sinhala, Tamil; LKR Sri Lankan rupee

Holiday snapshot: No holiday snapshot attached for the current year.

JST

Japan

1,296 mapped city anchors; zones Asia/Tokyo.capital Tokyo; Japanese; JPY Japanese yen

Holiday snapshot: New Year's Day (Jan 1, Public) · Coming of Age Day (Jan 12, Public) · Foundation Day (Feb 11, Public) · The Emperor's Birthday (Feb 23, Public) · Vernal Equinox Day (Mar 20, Public)

Neighboring abbreviation checks

These are the labels most likely to be confused with either side of this conversion. A matching UTC offset does not mean the same country, calendar, market, source convention, or user intent.

From side: IOT

nearby

IST and IOT are close enough to be confused in search, but they are not the same clock label and should be pinned to exact IANA zones.

Current side: IST: India Time via Asia/Kolkata, +05:30; cities Mumbai, India, Delhi, India, and Bengaluru, India; countries India, Israel, and Sri Lanka.
Neighbor side: IOT: Indian Ocean Time via Indian/Chagos, +06:00; cities No country breakdown available; countries British Indian Ocean Territory.

Open IOT

From side: AFT

nearby

IST and AFT are close enough to be confused in search, but they are not the same clock label and should be pinned to exact IANA zones.

Current side: IST: India Time via Asia/Kolkata, +05:30; cities Mumbai, India, Delhi, India, and Bengaluru, India; countries India, Israel, and Sri Lanka.
Neighbor side: AFT: Afghanistan Time via Asia/Kabul, +04:30; cities Kabul, Afghanistan, Herāt, Afghanistan, and Kandahār, Afghanistan; countries Afghanistan.

Open AFT

From side: BST

nearby

IST and BST are close enough to be confused in search, but they are not the same clock label and should be pinned to exact IANA zones.

Current side: IST: India Time via Asia/Kolkata, +05:30; cities Mumbai, India, Delhi, India, and Bengaluru, India; countries India, Israel, and Sri Lanka.
Neighbor side: BST: Bangladesh Time via Asia/Dhaka, +06:00; cities Dhaka, Bangladesh, London, United Kingdom, and Abidjan, Ivory Coast; countries Bangladesh, United Kingdom, and Ivory Coast.

Open BST

From side: BTT

nearby

IST and BTT are close enough to be confused in search, but they are not the same clock label and should be pinned to exact IANA zones.

Current side: IST: India Time via Asia/Kolkata, +05:30; cities Mumbai, India, Delhi, India, and Bengaluru, India; countries India, Israel, and Sri Lanka.
Neighbor side: BTT: Bhutan Time via Asia/Thimphu, +06:00; cities Thimphu, Bhutan, Phuntsholing, Bhutan, and Tsirang, Bhutan; countries Bhutan.

Open BTT

From side: CCT

nearby

IST and CCT are close enough to be confused in search, but they are not the same clock label and should be pinned to exact IANA zones.

Current side: IST: India Time via Asia/Kolkata, +05:30; cities Mumbai, India, Delhi, India, and Bengaluru, India; countries India, Israel, and Sri Lanka.
Neighbor side: CCT: Cocos Islands Time via Indian/Cocos, +06:30; cities West Island, Cocos Islands; countries Cocos Islands.

Open CCT

From side: FSAT

nearby

IST and FSAT are close enough to be confused in search, but they are not the same clock label and should be pinned to exact IANA zones.

Current side: IST: India Time via Asia/Kolkata, +05:30; cities Mumbai, India, Delhi, India, and Bengaluru, India; countries India, Israel, and Sri Lanka.
Neighbor side: FSAT: French Southern & Antarctic Time via Indian/Kerguelen, +05:00; cities Port-aux-Français, French Southern Territories; countries French Southern Territories.

Open FSAT

To side: GMT+9

same offset

JST and GMT+9 match on offset right now, but the page should not collapse them: they carry different city anchors, country calendars, currencies, holidays, and user intent.

Current side: JST: Japan Time via Asia/Tokyo, +09:00; cities Tokyo, Japan, Yokohama, Japan, and Osaka, Japan; countries Japan.
Neighbor side: GMT+9: Timor-Leste Time via Asia/Dili, +09:00; cities Dili, Timor Leste, Maliana, Timor Leste, and Suai, Timor Leste; countries Timor Leste.

Open GMT+9

To side: KST

same offset

JST and KST match on offset right now, but the page should not collapse them: they carry different city anchors, country calendars, currencies, holidays, and user intent.

Current side: JST: Japan Time via Asia/Tokyo, +09:00; cities Tokyo, Japan, Yokohama, Japan, and Osaka, Japan; countries Japan.
Neighbor side: KST: Korean Time via Asia/Seoul, +09:00; cities Seoul, South Korea, Busan, South Korea, and Pyongyang, North Korea; countries South Korea and North Korea.

Open KST

To side: PWT

same offset

JST and PWT match on offset right now, but the page should not collapse them: they carry different city anchors, country calendars, currencies, holidays, and user intent.

Current side: JST: Japan Time via Asia/Tokyo, +09:00; cities Tokyo, Japan, Yokohama, Japan, and Osaka, Japan; countries Japan.
Neighbor side: PWT: Palau Time via Pacific/Palau, +09:00; cities Ngerulmud, Palau; countries Palau.

Open PWT

To side: WIT

same offset

JST and WIT match on offset right now, but the page should not collapse them: they carry different city anchors, country calendars, currencies, holidays, and user intent.

Current side: JST: Japan Time via Asia/Tokyo, +09:00; cities Tokyo, Japan, Yokohama, Japan, and Osaka, Japan; countries Japan.
Neighbor side: WIT: Eastern Indonesia Time via Asia/Jayapura, +09:00; cities Jayapura, Indonesia, Ambon, Indonesia, and Sorong, Indonesia; countries Indonesia.

Open WIT

To side: YAKT

same offset

JST and YAKT match on offset right now, but the page should not collapse them: they carry different city anchors, country calendars, currencies, holidays, and user intent.

Current side: JST: Japan Time via Asia/Tokyo, +09:00; cities Tokyo, Japan, Yokohama, Japan, and Osaka, Japan; countries Japan.
Neighbor side: YAKT: Yakutsk Time via Asia/Chita, +09:00; cities Chita, Russia, Krasnokamensk, Russia, and Borzya, Russia; countries Russia.

Open YAKT

To side: ACDT

nearby

JST and ACDT are close enough to be confused in search, but they are not the same clock label and should be pinned to exact IANA zones.

Current side: JST: Japan Time via Asia/Tokyo, +09:00; cities Tokyo, Japan, Yokohama, Japan, and Osaka, Japan; countries Japan.
Neighbor side: ACDT: Australian Central Time via Australia/Adelaide, +09:30; cities Adelaide, Australia, Darwin, Australia, and Adelaide Hills, Australia; countries Australia.

Open ACDT

Jurisdiction and city roster

Abbreviations with the same UTC offset can still represent different countries, cities, currencies, languages, and civil-time histories. This roster keeps theIST to JST page grounded in those concrete places.

IST: Israel (IL); 108 mapped cities; zones Asia/Jerusalem; city anchors Jerusalem (Asia/Jerusalem, pop 971,800), Tel Aviv (Asia/Jerusalem, pop 432,892), West Jerusalem (Asia/Jerusalem, pop 400,000), Haifa (Asia/Jerusalem, pop 285,316); official State of Israel; capital Jerusalem; region Asia; subregion Western Asia; population 10,134,800; area 21,937 km2; languages Arabic, Hebrew; currency ILS Israeli new shekel.

IST: Sri Lanka (LK); 60 mapped cities; zones Asia/Colombo; city anchors Colombo (Asia/Colombo, pop 648,034), Dehiwala-Mount Lavinia (Asia/Colombo, pop 219,827), Maharagama (Asia/Colombo, pop 195,355), Jaffna (Asia/Colombo, pop 169,102); official Democratic Socialist Republic of Sri Lanka; capital Sri Jayawardenepura Kotte; region Asia; subregion Southern Asia; population 21,763,170; area 65,610 km2; languages Sinhala, Tamil; currency LKR Sri Lankan rupee.

JST: Japan (JP); 1296 mapped cities; zones Asia/Tokyo; city anchors Tokyo (Asia/Tokyo, pop 9,733,276), Yokohama (Asia/Tokyo, pop 3,777,491), Osaka (Asia/Tokyo, pop 2,753,862), Nagoya (Asia/Tokyo, pop 2,332,176); official Japan; capital Tokyo; region Asia; subregion Eastern Asia; population 123,210,000; area 377,930 km2; languages Japanese; currency JPY Japanese yen.

Abbreviation identity dossier

Same-offset converter pages can look deceptively alike. These records pin the page to the exact abbreviations, IANA zones, countries, and city anchors behind IST and JST.

From side meaning roster

IST (ist) is ambiguous in the abbreviation catalog. Meaning records: Israel Time at UTC+02:00; listed zones Asia/Jerusalem; source label Israel Time - Jerusalem, Tel Aviv, West Jerusalem, Haifa | India Time at UTC+05:30; listed zones Asia/Colombo; Asia/Kolkata; source label India Time - Colombo, Dehiwala-Mount Lavinia, Maharagama, Jaffna.

From side country footprint

IST currently maps to 3 country footprints in the converter dataset: India (IN), Israel (IL), Sri Lanka (LK). The footprint spans 3 IANA zones across 10 city anchors.

From side city anchors

IST city anchors in this indexed page family: Mumbai [mumbai-IN, IN, Asia/Kolkata, pop 12,691,836]; Delhi [delhi-IN, IN, Asia/Kolkata, pop 11,034,555]; Bengaluru [bengaluru-IN, IN, Asia/Kolkata, pop 8,495,492]; Hyderabad [hyderabad-IN, IN, Asia/Kolkata, pop 6,993,262]; Ahmedabad [ahmedabad-IN, IN, Asia/Kolkata, pop 6,357,693]; Chennai [chennai-IN, IN, Asia/Kolkata, pop 4,681,087]; Kolkata [kolkata-IN, IN, Asia/Kolkata, pop 4,631,392]; Surat [surat-IN, IN, Asia/Kolkata, pop 4,591,246]; Pune [pune-IN, IN, Asia/Kolkata, pop 3,124,458]; Jaipur [jaipur-IN, IN, Asia/Kolkata, pop 3,046,163].

From side jurisdiction dossier

IST: India (IN); 3776 mapped cities; zones Asia/Kolkata; city anchors Mumbai (Asia/Kolkata, pop 12,691,836), Delhi (Asia/Kolkata, pop 11,034,555), Bengaluru (Asia/Kolkata, pop 8,495,492), Hyderabad (Asia/Kolkata, pop 6,993,262); official Republic of India; capital New Delhi; region Asia; subregion Southern Asia; population 1,417,492,000; area 3,287,263 km2; languages English, Hindi, Tamil; currency INR Indian rupee. IST: Israel (IL); 108 mapped cities; zones Asia/Jerusalem; city anchors Jerusalem (Asia/Jerusalem, pop 971,800), Tel Aviv (Asia/Jerusalem, pop 432,892), West Jerusalem (Asia/Jerusalem, pop 400,000), Haifa (Asia/Jerusalem, pop 285,316); official State of Israel; capital Jerusalem; region Asia; subregion Western Asia; population 10,134,800; area 21,937 km2; languages Arabic, Hebrew; currency ILS Israeli new shekel. IST: Sri Lanka (LK); 60 mapped cities; zones Asia/Colombo; city anchors Colombo (Asia/Colombo, pop 648,034), Dehiwala-Mount Lavinia (Asia/Colombo, pop 219,827), Maharagama (Asia/Colombo, pop 195,355), Jaffna (Asia/Colombo, pop 169,102); official Democratic Socialist Republic of Sri Lanka; capital Sri Jayawardenepura Kotte; region Asia; subregion Southern Asia; population 21,763,170; area 65,610 km2; languages Sinhala, Tamil; currency LKR Sri Lankan rupee.

To side meaning roster

JST (jst) is not marked ambiguous in the abbreviation catalog. Meaning records: Japan Time at UTC+09:00; listed zones Asia/Tokyo; source label Japan Time - Tokyo, Yokohama, Osaka, Nagoya.

To side country footprint

JST currently maps to 1 country footprint in the converter dataset: Japan (JP). The footprint spans 1 IANA zone across 10 city anchors.

To side city anchors

JST city anchors in this indexed page family: Tokyo [tokyo-JP, JP, Asia/Tokyo, pop 9,733,276]; Yokohama [yokohama-JP, JP, Asia/Tokyo, pop 3,777,491]; Osaka [osaka-JP, JP, Asia/Tokyo, pop 2,753,862]; Nagoya [nagoya-JP, JP, Asia/Tokyo, pop 2,332,176]; Sapporo [sapporo-JP, JP, Asia/Tokyo, pop 1,973,832]; Fukuoka [fukuoka-JP, JP, Asia/Tokyo, pop 1,612,392]; Kawasaki [kawasaki-JP, JP, Asia/Tokyo, pop 1,538,262]; Kobe [kobe-JP, JP, Asia/Tokyo, pop 1,525,152]; Kyoto [kyoto-JP, JP, Asia/Tokyo, pop 1,463,723]; Saitama [saitama-JP, JP, Asia/Tokyo, pop 1,324,854].

To side jurisdiction dossier

From side timezone narrative

IST is reused across 2 different meanings in this dataset — India Time and Israel Time — which is why the short code alone is not enough to identify a place. Each meaning maps to its own IANA zone family and its own DST behavior, and they happen to share the same letters by historical accident more than by design. The busiest cities using IST in the current catalog are Mumbai, Delhi, Bengaluru, Hyderabad, and Ahmedabad. The lead live reference on this page is Mumbai (Asia/Kolkata), currently at +05:30 (GMT+5:30). Those cities are what give IST its actual feel rather than the abstract offset. Because IST spans UTC+02:00 to UTC+05:30 across the active meanings, software, calendars, and contracts should always pin a specific IANA zone such as Asia/Kolkata or a literal UTC offset. The short label is fine for headlines and chat; it is the wrong primitive for storing or scheduling timestamps.

From side policy and precision notes

IST appears with 2 distinct meanings in current data, splitting across UTC+02:00 to UTC+05:30. The short label looks tidy in writing but quietly hides which place you mean — pick a city, a country, or an IANA zone before it matters. Asia/Kolkata does not show an offset change in the next year, which makes IST predictable for short-term scheduling. Predictable is not the same as permanent — civil-time rules still get changed by governments on relatively short notice. For precise work, the safest equivalent of IST is the exact IANA zone used by your city or system. Asia/Kolkata sits at +05:30, ahead of UTC, which means daily logs in this zone reach a new calendar date before UTC does — a small detail that breaks date-based reporting if missed.

From side nearby abbreviations

IST should not be blindly swapped with nearby labels. Adjacent references in the catalog: IOT (+06:00, Runs on a nearby UTC offset); AFT (+04:30, Runs on a nearby UTC offset); BST (+06:00, Runs on a nearby UTC offset); BTT (+06:00, Runs on a nearby UTC offset); CCT (+06:30, Runs on a nearby UTC offset); FSAT (+05:00, Runs on a nearby UTC offset).

From side answer profile

IST has 2 meaning records, offset range UTC+02:00 to UTC+05:30, labels India Time, Israel Time, and 3 country footprints across 3 IANA zones.

To side timezone narrative

JST is an Asian civil-time label, currently 9h ahead of UTC at +09:00. The lead reference is Tokyo, and the wider grouping reaches 1 country through 1 IANA zone. The busiest cities using JST in the current catalog are Tokyo, Yokohama, Osaka, Nagoya, and Sapporo. The lead live reference on this page is Tokyo (Asia/Tokyo), currently at +09:00 (GMT+9). Those cities are what give JST its actual feel rather than the abstract offset. JST is stable on Asia/Tokyo year-round, with no seasonal clock changes in the next year. That makes it a low-friction choice for recurring meetings and broadcast schedules — but software still prefers the IANA zone because governments can change civil-time rules independently of the short code.

To side policy and precision notes

JST resolves cleanly here, but Asian labels often share letters with American or European ones — IST is shared between India and Israel, for instance. Pinning Asia/Tokyo avoids that whole class of confusion. Asia/Tokyo does not show an offset change in the next year, which makes JST predictable for short-term scheduling. Predictable is not the same as permanent — civil-time rules still get changed by governments on relatively short notice. For precise work, the safest equivalent of JST is the exact IANA zone used by your city or system. Asia/Tokyo sits at +09:00, ahead of UTC, which means daily logs in this zone reach a new calendar date before UTC does — a small detail that breaks date-based reporting if missed.

To side nearby abbreviations

JST should not be blindly swapped with nearby labels. Adjacent references in the catalog: GMT+9 (+09:00, Currently sits on the same UTC offset); KST (+09:00, Currently sits on the same UTC offset); PWT (+09:00, Currently sits on the same UTC offset); WIT (+09:00, Currently sits on the same UTC offset); YAKT (+09:00, Currently sits on the same UTC offset); ACDT (+09:30, Runs on a nearby UTC offset).

To side answer profile

JST has 1 meaning record, offset range UTC+09:00, labels Japan Time, and 1 country footprint across 1 IANA zone.

From side country reference summary

IST country anchor India: India, officially the Republic of India, is a country in South Asia. It is the seventh-largest country by area; the most populous country in the world and, since its independence in 1947, the world's most populous democracy. Bounded by the Indian Ocean on the south, the Arabian Sea on the southwest, and the Bay of Bengal on the southeast, it shares land borders with Pakistan to the west; China, Nepal and Bhutan to the north; Bangladesh and Myanmar to the east. In the Indian Ocean, India is near Sri Lanka and the Maldives. Its Andaman and Nicobar Islands share a maritime border with Myanmar, Thailand and Indonesia. Source: Wikipedia.

To side country reference summary

JST country anchor Japan: Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asian mainland, it is bordered to the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea in the south. The Japanese archipelago consists of four major islands alongside 14,121 smaller islands. Japan is divided into 47 administrative prefectures and eight traditional regions, and around 75% of its terrain is mountainous and heavily forested, concentrating its agriculture and highly urbanized population along its eastern coastal plains. With a population of almost 123 million as of 2026, it is the world's 11th most populous country. Tokyo is the country's capital and largest city. Source: Wikipedia.

To side trust note 1

To side trust note 2

Pair identity check

IST/JST uses Asia/Kolkata -> Asia/Tokyo, offset delta +3h 30m, overlap 4.5h, route /convert/ist/jst/, and live abbreviation readings GMT+5:30/GMT+9.

Reference data for IST to JST

Reference fields include this converter pair's abbreviation records, representative IANA zones, current offsets, city anchors, country profiles, overlap math, conversion examples, and dossier notes.

israeltimejerusalemtelavivwestjerusalemhaifaindiatimecolombodehiwalamountlaviniamaharagamajaffnajapantimetokyoyokohamaosakanagoyaasiakolkataasiatokyoindiatimejapantime900ampreviousday130pmpreviousdaysrilankamumbaiinbengaluruinbengaluruhyderabadinhyderabadyokohamajpyokohamanagoyajpnewdelhiindianrupeesouthernasiajerusalemisraelinewshekelwesternasiasrijayawardenepurakottesrilankanrupeejapanesejapaneseyeneasternasiacapitalnewdelhienglishhinditamilinrindianrupeeasiajerusalemcapitaljerusalemarabichebrewilsisraelinewshekelnoholidaysnapshotattachedforthecurrentyearasiacolombocapitalsrijayawardenepurakottesinhalatamillkrsrilankanrupeecapitaltokyojapanesejpyjapaneseyenreferencepairasiakolkataasiatokyoliveoffsetsist0530vsjst0900meaningsplitindiatimejapantimecountryanchorsindiaisraelandsrilankajapancityanchorsmumbaidelhibengaluruhyderabadtokyoyokohamaosakanagoyaworkdayoverlap45hwindowist900ampreviousday130pmpreviousdaymorninganswer9amist1230pmjstsamedayeveninganswer6pmist930pmjstsamedayjstlocalintent1jstlocalintent2exactpairidentitycivilcalendardifferencessameoffsetcautionjurisdictionevidenceoffsetbehaviorclassdstasymmetrycheckcalendarevidencedayshiftfingerprintindexingposturesameoffsetmathcheckneighborauditcanonicalevidencefromsiderunsonanearbyutcoffsetcurrentlysitsonthesameutcoffsetpwtpalautimeviapacificpalau0900citiesngerulmudpalaucountriespalaufromsidemeaningrosterfromsidecountryfootprintfromsidecityanchorsfromsidejurisdictiondossiertosidemeaningrostertosidecountryfootprinttosidecityanchorstosidejurisdictiondossierfromsidetimezonenarrativefromsidepolicyandprecisionnotesfromsidenearbyabbreviationsfromsideanswerprofiletosidetimezonenarrativetosidepolicyandprecisionnotestosidenearbyabbreviationstosideanswerprofilefromsidecountryreferencesummarytosidecountryreferencesummarytosidetrustnote1tosidetrustnote2pairidentitycheckjstisraelisraeltimetimejerusalemjerusalemtelavivwestwestjerusalemjerusalemhaifahaifaindiatimecolombocolombodehiwaladehiwalamountmountlavinialaviniamaharagamamaharagamajaffnajaffnajapantimetokyotokyoyokohamayokohamaosakaosakanagoyanagoyaasiakolkataasiajstconnectsconnectsindiaindiaandandjapanjapanseparatedseparatedbyhoursthisthisconversion

Market coverage on both sides

IST coverage on this page is led by Mumbai, India, Delhi, India, Bengaluru, India, and Hyderabad, India, with 2 more in the live dataset. That mix is what makes IST feel anchored to South and Southeast Asian business hubs in practice rather than just an abbreviation on a chart.

JST coverage is led by Tokyo, Japan, Yokohama, Japan, Osaka, Japan, and Nagoya, Japan, with 2 more anchoring the wider label family. Combined with the IST side, this conversion ends up describing intra-Asia regional logistics and travel coordination.

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From

Common meeting times

IST to JST meeting times

Quick conversions for 9 AM, noon, 3 PM, 6 PM, and 9 PM based on today's local calendar.

IST	JST	Day relation
9:00 AM	12:30 PMMon, May 25	same day
12:00 PM	3:30 PMMon, May 25	same day
3:00 PM	6:30 PMMon, May 25	same day
6:00 PM	9:30 PMMon, May 25	same day
9:00 PM	12:30 AMTue, May 26	next day

JST to IST meeting times

Quick conversions for 9 AM, noon, 3 PM, 6 PM, and 9 PM based on today's local calendar.

JST	IST	Day relation
9:00 AM	5:30 AMMon, May 25	same day
12:00 PM	8:30 AMMon, May 25	same day
3:00 PM	11:30 AMMon, May 25	same day
6:00 PM	2:30 PMMon, May 25	same day
9:00 PM	5:30 PMMon, May 25	same day

Operational notes

IST to JST ranges from IST 9:00 AM (which lands at JST 12:30 PM) through IST 9:00 PM (JST 12:30 AM). Across this +3h 30m gap, the middle of the IST range usually lands in the JST afternoon — the reliable window for live calls between the two — while the early and late edges drift into JST morning or evening.

JST to IST ranges from JST 9:00 AM (which lands at IST 5:30 AM) through JST 9:00 PM (IST 5:30 PM). Across this +3h 30m gap, the middle of the JST range usually lands in the IST afternoon — the reliable window for live calls between the two — while the early and late edges drift into IST morning or evening.

Overlap window and DST radar

The live gap is +3h 30m right now, based on Asia/Kolkata at +05:30 and Asia/Tokyo at +09:00. Neither reference zone shows an offset change in the next year, so the gap should stay stable.

The most usable workday block right now is about 4.5 hours: IST 9:00 AM previous day to 1:30 PM previous day, which lines up with JST 12:30 PM previous day to 5:00 PM previous day.

Reference zones

Asia/Kolkata

GMT+5:30 · +05:30

Asia/Tokyo

GMT+9 · +09:00

These are the busiest live references selected from the abbreviation families on this page.

Conversion Table

IST	JST
05:30	09:00
06:30	10:00
07:30	11:00
08:30	12:00
09:30	13:00
10:30	14:00
11:30	15:00
12:30	16:00
13:30	17:00
14:30	18:00
15:30	19:00
16:30	20:00
17:30	21:00
18:30	22:00
19:30	23:00
20:30	00:00
21:30	01:00
22:30	02:00
23:30	03:00
00:30	04:00
01:30	05:00
02:30	06:00
03:30	07:00
04:30	08:00

Top cities using IST

Countries represented here include India, Israel, and Sri Lanka.

MumbaiIndia DelhiIndia BengaluruIndia HyderabadIndia

Top cities using JST

Countries represented here include Japan.

TokyoJapan YokohamaJapan OsakaJapan NagoyaJapan

FAQ

How many hours is JST ahead of IST?: JST is currently +3h 30m relative to IST, using Asia/Kolkata and Asia/Tokyo as the live reference zones on this page.
What is the best workday overlap between IST and JST?: The current 9-to-5 overlap is about 4.5 hours: IST 9:00 AM previous day to 1:30 PM previous day, which matches JST 12:30 PM previous day to 5:00 PM previous day.
Does the IST-JST time difference change during DST?: The live gap is +3h 30m right now, based on Asia/Kolkata at +05:30 and Asia/Tokyo at +09:00. Neither reference zone shows an offset change in the next year, so the gap should stay stable.
Which cities commonly use IST and JST?: IST commonly covers cities such as Mumbai, Delhi, Bengaluru, and Hyderabad, while JST commonly covers cities such as Tokyo, Yokohama, Osaka, and Nagoya.
Should I use IST/JST or exact IANA zones?: Use the abbreviations for a quick read, but use exact IANA zones such as Asia/Kolkata and Asia/Tokyo when you need something precise in software, travel plans, or long-range scheduling.

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Related Conversions

EST → IST EST → JST PST → IST PST → JST CST → IST CST → JST MST → IST MST → JST GMT → IST GMT → JST UTC → IST UTC → JST

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IST to JST Converter.

Ambiguity note

IST

JST

Scheduling snapshot

Pair context

Pair details

Calendar and scheduling context

Exact pair identity

Civil calendar differences

Same-offset caution

Jurisdiction evidence

Pair fingerprint

Offset behavior class

DST asymmetry check

Calendar evidence

Day-shift fingerprint

Same-offset and canonical audit

Indexing posture

Same-offset math check

Neighbor audit

Canonical evidence

Local intent behind each abbreviation

JST local intent 1

JST local intent 2

Country calendar contrast

India

Israel

Sri Lanka

Japan

Neighboring abbreviation checks

From side: IOT

From side: AFT

From side: BST

From side: BTT

From side: CCT

From side: FSAT

To side: GMT+9

To side: KST

To side: PWT

To side: WIT

To side: YAKT

To side: ACDT

Jurisdiction and city roster

Abbreviation identity dossier

From side meaning roster

From side country footprint

From side city anchors

From side jurisdiction dossier

To side meaning roster

To side country footprint

To side city anchors

To side jurisdiction dossier

From side timezone narrative

From side policy and precision notes

From side nearby abbreviations

From side answer profile

To side timezone narrative

To side policy and precision notes

To side nearby abbreviations

To side answer profile

From side country reference summary

To side country reference summary

To side trust note 1

To side trust note 2

Pair identity check

Market coverage on both sides

Digit-roll converter

Common meeting times

IST to JST meeting times

JST to IST meeting times

Operational notes

Popular hour answers

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