What is the time difference between IST and EST?

IST is 9.5 hours ahead of EST in winter (US Standard Time, Nov-Mar) and 9.5 hours ahead of EDT in summer (US Daylight Saving, Mar-Nov). 8:00 AM IST = 10:30 PM EST (previous day) in winter; = 10:30 PM EDT in summer. The difference of 9.5 stays constant; only the EST/EDT label changes.

How many hours behind IST is California (PST)?

California is 12.5 hours behind IST in winter (PST) and 12.5 hours behind IST in summer (PDT). 9:00 AM IST = 8:30 PM previous-day PST in winter; = 8:30 PM previous-day PDT in summer. This calculator handles DST automatically.

Does India observe daylight saving time?

No. India does not observe daylight saving time (DST). IST (Indian Standard Time) stays constant at UTC+5:30 throughout the year. This makes IST predictable but means the offset to US/EU time zones changes twice a year as those countries shift in/out of DST.

What is UTC and how is it different from GMT?

UTC (Coordinated Universal Time) is the modern atomic-clock-based standard. GMT (Greenwich Mean Time) is the historical solar-based time at Greenwich, London. They are nearly identical (within 0.9 seconds). GMT is now mainly a time-zone label for UK winter; UTC is the technical standard used in scientific and computing contexts.

Why does my meeting time change between October and March?

Most US and European time zones observe daylight saving time — they shift forward 1 hour in March and back 1 hour in November. India doesn't shift, so meeting times effectively move by 1 hour twice a year. Schedule with explicit time-zone labels (e.g., '9 AM IST') rather than just '9 AM' to avoid confusion.

Time Zone Converter — IST to EST, PST, GMT, CET | IndCalc

Time Zone Converter

Convert any time between IST, EST, PST, GMT, CET, JST, AEST and 9+ more time zones. Built for remote-work meetings, international calls, and travel — with automatic daylight saving.

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IST and How It Compares to Other Zones

Indian Standard Time (IST) is UTC+5:30 — a half-hour offset because India spans only one time zone despite being geographically vast (the easternmost point in Arunachal sees sunrise nearly 2 hours before the westernmost point in Gujarat). India does not observe daylight saving time, so IST is constant year-round.

IST to US East Coast: 9.5 hours ahead in winter (when US is on EST), 9.5 hours ahead in summer (when US is on EDT). IST to US West Coast: 12.5 hours ahead in winter (PST), 12.5 hours ahead in summer (PDT). The 'half hour' offset is what catches most schedulers off-guard.

IST to UK: 5.5 hours ahead in winter (GMT), 4.5 hours ahead in summer (BST). IST to Europe (most of mainland): 4.5 hours ahead in winter (CET), 3.5 hours ahead in summer (CEST). IST to Singapore/Hong Kong: 2.5 hours behind. IST to Tokyo: 3.5 hours behind. IST to Sydney: 4.5 hours behind in their winter, 5.5 in their summer.

Daylight Saving Time — Why It Matters

Most of the US and Europe shifts forward 1 hour on the second Sunday of March and back 1 hour on the first Sunday of November. India doesn't observe DST. So if you book a recurring 9 AM IST meeting with a US team, the US local time effectively shifts by 1 hour twice a year — March ('spring forward') and November ('fall back').

This calculator uses the IANA time-zone database (via the browser's Intl API) which includes all historical DST rule changes. The result is always accurate for the specific date you choose — including dates spanning DST transitions.

Best practice for international meetings: always specify the time zone label ('9 AM IST', not just '9 AM'). Use tools like this to verify the converted time before sending invites. Calendar apps like Google Calendar handle DST shifts automatically if you set the meeting in a specific time zone — but the original organizer's TZ is what 'wins'.

Common Remote-Work Schedules

India ↔ US East Coast (overlap window): 7-9 PM IST = 9-11 AM EST. Indian evening matches US morning — the most popular working window for transatlantic teams.

India ↔ US West Coast (limited overlap): 9-11 PM IST = 8:30-10:30 AM PST. Late evenings in India align with morning in California. Teams with deeper US-West engagement often have one Indian team member work 1-2 PM to 10 PM IST.

India ↔ UK (huge overlap): 1-9 PM IST = 7:30 AM - 3:30 PM GMT. Best transatlantic-style overlap globally. UK winter time is just 5.5 hours behind IST — most of the working day overlaps.

India ↔ Singapore/Hong Kong: 2.5 hours behind IST means 11 AM IST = 1:30 PM SGT. Practical day-overlap of 6-8 hours. Best for APAC-aligned roles.

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