IST to JST

About India Standard Time

India keeps one clock, UTC+5:30, across a country spanning about 29 degrees of longitude — the sun rises nearly two hours earlier in Arunachal Pradesh than in Gujarat on the same clock. The half-hour offset means most conversions from India land on the half hour rather than the hour. Sri Lanka keeps the same time.

Cities on this clock: Mumbai, Delhi, Bangalore, Hyderabad, Chennai, Kolkata, Pune, Ahmedabad.

Watch out: IST is also Israel Standard Time (UTC+2) and Irish Standard Time (UTC+1). This page is the Indian one.

About Japan Standard Time

Japan is a fixed UTC+9 and has had no daylight saving since 1951. It shares its clock with Korea exactly, so a schedule that works for Tokyo works unchanged for Seoul.

Cities on this clock: Tokyo, Osaka, Seoul.

How the difference is worked out

Neither India Standard Time nor Japan Standard Time moves its clock relative to the other, so japan standard time is 3 hours 30 minutes ahead of india standard time is a rule rather than a fact about one particular year. The hour-by-hour table above holds on every date.

With both zones on their own standard time — daylight saving not in force anywhere — Japan Standard Time is 3 hours 30 minutes ahead of India Standard Time. That figure never changes; everything else on this page follows from it plus whichever clocks have moved.

Every figure here comes from the IANA time zone database via your browser's own Intl engine, using the zone ids Asia/Kolkata and Asia/Tokyo. Nothing is looked up on a server and nothing about your visit is recorded.