Timezone Converter
Convert time between any two timezones with automatic daylight saving support — free, instant, no signup
From
To
What is this Timezone Converter?
This free timezone converter lets you convert any date and time between two timezones anywhere in the world — with automatic daylight saving time (DST) adjustment applied for the exact date you select. It uses your browser's built-in Intl.DateTimeFormat API backed by the full IANA timezone database, which is the same standard used by all major operating systems, programming languages, and services like Google Calendar. This means the conversion is always accurate, including half-hour offsets like India (UTC+5:30), 45-minute offsets like Nepal (UTC+5:45), and DST transitions that change on different dates in different countries.
The sidebar shows a live world clock for six major global cities — New York, London, New Delhi, Beijing, Tokyo, and Sydney — updating every second. The result panel shows both the From and To times side by side with full date (including day of week, to catch International Date Line crossings), plus a sentence explaining how many hours and minutes ahead or behind the target timezone is.
How to use this converter — step by step
- Step 1 — Set the date: The current date is pre-filled. Change it for any past or future date — for example, to check what time a US deadline is in India, or to plan a future international call. DST rules are applied correctly for whatever date you enter.
- Step 2 — Set the time: The current time is pre-filled. Change it to the time you want to convert — enter it in the "From" timezone's local time.
- Step 3 — Select From timezone: Choose the timezone the time is currently in. For IST (India Standard Time), select "Kolkata (GMT+5:30)". The dropdown shows the city name and current UTC offset for easy identification.
- Step 4 — Select To timezone: Choose the timezone you want to convert to. Results update immediately whenever you change any field — no need to click Convert.
- Step 5 — Click "Convert time" or read the live result: The result shows time and full date in both timezones, plus the difference banner (e.g. "London is 5 hrs 30 mins behind New Delhi").
- Step 6 — Check the date carefully: When converting across the International Date Line or late-night times, the date in the "To" box may be a day earlier or later than the "From" date. Always read both the time and date in the result.
- Step 7 — Reset: Click Reset to return to current date/time with the default IST → London pair.
Key features
- Full IANA timezone database: 60+ major timezones across Asia, Europe, Americas, Africa, and Pacific — including every non-standard offset
- Automatic DST adjustment: Correct daylight saving rules applied for the specific date — no manual offset guessing
- Past and future dates: Works for any date, not just today — plan future meetings or verify past event times
- Time difference banner: Shows exactly how many hours and minutes the target timezone is ahead of or behind the source
- Live world clock: Real-time display for 6 global cities, updated every second
- Date line awareness: Shows full date in result so you catch next-day or previous-day crossings
Timezones, UTC, DST and IST — a complete practical guide
Timezone conversion is one of those tasks that feels simple until you do it wrong — miss a DST transition, cross the date line without noticing, or confuse ET with EDT — and you show up for a meeting an hour early, a day late, or miss a deadline entirely. This guide explains everything you need to know to convert accurately.
What is UTC and why does everything reference it?
UTC (Coordinated Universal Time) is the global time standard — it has no offset, no daylight saving, and never changes. Every timezone in the world is defined as UTC plus or minus some number of hours (and sometimes half-hours or 45 minutes). UTC replaced GMT (Greenwich Mean Time) as the international standard in 1972, though they differ by less than a second and the terms are often used interchangeably in everyday contexts.
UTC is important because it gives every moment in time a single, unambiguous label. When a company says "our server maintenance is at 02:00 UTC," every person in every country can look up their local equivalent without ambiguity. This converter does that lookup automatically.
India Standard Time (IST) — UTC+5:30
India observes a single timezone nationwide: IST (India Standard Time), UTC+5:30. It is one of the few countries in the world with a 30-minute offset — a historical compromise when India was unified under a single timezone in 1905. India does not observe daylight saving time, making IST conversions simpler than converting to/from US or European timezones. Key IST conversions:
- IST to EST (US Eastern Standard Time, UTC-5): IST is 10 hours 30 minutes ahead of EST. When EST observes EDT (UTC-4, from mid-March to early November), IST is 9 hours 30 minutes ahead.
- IST to PST (US Pacific Standard Time, UTC-8): IST is 13 hours 30 minutes ahead. During PDT (UTC-7, summer), IST is 12 hours 30 minutes ahead.
- IST to GMT/BST (UK): IST is 5 hours 30 minutes ahead of GMT (winter). During BST (British Summer Time, UTC+1, late March to late October), IST is only 4 hours 30 minutes ahead.
- IST to CET (Central European Time, UTC+1): IST is 4 hours 30 minutes ahead. During CEST (UTC+2), IST is 3 hours 30 minutes ahead.
- IST to SGT/HKT/CST (Singapore, Hong Kong, China — all UTC+8): IST is 2 hours 30 minutes behind. These do not observe DST, so this offset is constant year-round.
- IST to JST (Japan, UTC+9): IST is 3 hours 30 minutes behind. Japan does not observe DST — constant offset.
- IST to AEST (Sydney, UTC+10): IST is 4 hours 30 minutes behind AEST. During AEDT (UTC+11, October–April), IST is 5 hours 30 minutes behind.
- IST to Dubai (UAE, UTC+4): IST is 1 hour 30 minutes ahead. UAE does not observe DST — constant offset.
Daylight Saving Time (DST) — the biggest source of conversion errors
Daylight Saving Time (DST) is the practice of advancing clocks by 1 hour during summer months to make better use of natural daylight. When DST is active, a timezone that is normally UTC-5 (EST) becomes UTC-4 (EDT). This makes conversions from India to the US different depending on the time of year — and the transition dates differ between countries, creating a 2–3 week window each spring and autumn when conversion offsets are inconsistent even between countries that both observe DST.
Key DST dates to know (approximate, varies slightly by year)
United States
Clocks spring forward (to EDT/CDT/MDT/PDT) on the 2nd Sunday of March. Fall back (to EST/CST/MST/PST) on the 1st Sunday of November. Exception: Arizona does not observe DST (stays on MST year-round).
Europe (EU)
Clocks spring forward (to BST/CEST etc.) on the last Sunday of March. Fall back on the last Sunday of October. The EU has proposed abolishing DST but it remains in effect. UK follows the same schedule independently.
No DST countries
India, China, Japan, Singapore, UAE, Saudi Arabia, Pakistan, Bangladesh, Sri Lanka, and most of Southeast Asia do not observe DST. Conversions between these countries have constant, year-round offsets.
Common real-world timezone conversion scenarios
Scheduling a call between India and the US: A 10:00 AM New York meeting in summer (EDT, UTC-4) = 10:00 AM + 9:30 = 7:30 PM IST. The same meeting in winter (EST, UTC-5) = 10:00 AM + 10:30 = 8:30 PM IST. The 1-hour DST shift moves the Indian equivalent by a full hour — always use this converter for upcoming meeting times rather than calculating manually.
Flight arrival time conversion: Your flight from Mumbai lands in London at 06:30 BST (summer). BST = UTC+1. IST = UTC+5:30. Mumbai departure: 06:30 BST − 4:30 = 02:00 AM IST previous day? No — 06:30 BST means it's 6:30 AM in London on, say, Tuesday. In India at that same moment it is 6:30 AM + 4:30 = 11:00 AM Tuesday IST. Use the converter: set "From" to London, "To" to Kolkata, enter the arrival time — it handles the math instantly.
Stock market trading hours from India: US markets (NYSE, NASDAQ) open at 9:30 AM ET. During summer (EDT): 9:30 AM + 9:30 = 7:00 PM IST. During winter (EST): 9:30 AM + 10:30 = 8:00 PM IST. London Stock Exchange opens at 8:00 AM GMT (winter) = 1:30 PM IST. During BST: 8:00 AM + 4:30 = 12:30 PM IST.
Remote work across continents: A product manager in Bengaluru (IST) working with a team in San Francisco (PST/PDT) and London (GMT/BST). In Indian summer (April–June): SF = PDT (UTC-7), IST is 12:30 hours ahead. London = BST (UTC+1), IST is 4:30 hours ahead. A 10:00 AM IST standup = 9:30 PM previous evening in SF, 5:30 AM in London. Clearly not workable — a more suitable overlap is 5:00–6:00 PM IST = 4:30–5:30 AM SF (early for SF) / 12:30–1:30 PM London (good for London). Use this converter to find overlap windows.
International Date Line crossings: When it is 11:00 PM Monday in Los Angeles (PDT, UTC-7), in Tokyo (JST, UTC+9) it is 11:00 PM + 16 hours = 3:00 PM Tuesday. The date has jumped. This converter shows the full date (including day name) in both result boxes, so you always notice day crossings. Missing this causes serious planning errors — booking a return flight "the same day" when the arrival is the next calendar day, for example.
The International Date Line and when the day changes
The International Date Line (IDL) runs roughly along the 180° meridian in the Pacific Ocean. Crossing it westward (travelling from US to Asia) moves you forward a day; crossing it eastward (Asia to US) moves you back a day. This is why Tokyo is always "tomorrow" relative to New York — even though New York is ahead of most of the world, Japan is ahead by enough hours that the calendar date rolls over. When this converter shows a different date in the "To" box, that is why.
Free, instant, DST-accurate — works for any date, past or future.
Frequently asked questions
Does this converter automatically handle daylight saving time?
Yes — fully automatically. This converter uses your browser's Intl.DateTimeFormat API, which reads the IANA (Internet Assigned Numbers Authority) timezone database — the same database used by all major operating systems (Windows, macOS, Linux, Android, iOS), Google Calendar, and international scheduling tools. When you select a date and a timezone, the browser looks up the exact DST rules for that timezone on that specific date and applies them without any manual input from you. For example: if you select New York on July 15, the converter automatically knows that EDT (UTC-4) applies, not EST (UTC-5). If you select New York on December 15, it correctly uses EST. The 2–3 week DST transition windows in March/November and the exact switch times are all handled correctly. Countries that do not observe DST (India, China, Japan, UAE, etc.) also work correctly — their offset never changes regardless of date.
What is the time difference between IST and other major timezones?
India Standard Time (IST, UTC+5:30) compared to major world timezones: IST vs EST (US East, winter): IST is 10 hours 30 minutes ahead. IST vs EDT (US East, summer): IST is 9 hours 30 minutes ahead. IST vs PST (US West, winter): IST is 13 hours 30 minutes ahead. IST vs PDT (US West, summer): IST is 12 hours 30 minutes ahead. IST vs GMT (UK, winter): IST is 5 hours 30 minutes ahead. IST vs BST (UK, summer): IST is 4 hours 30 minutes ahead. IST vs CET (Central Europe, winter): IST is 4 hours 30 minutes ahead. IST vs CEST (Central Europe, summer): IST is 3 hours 30 minutes ahead. IST vs GST (UAE/Dubai, year-round): IST is 1 hour 30 minutes ahead (constant — UAE has no DST). IST vs SGT/CST/HKT (Singapore, China, Hong Kong — all UTC+8, year-round): IST is 2 hours 30 minutes behind (constant). IST vs JST (Japan, UTC+9, year-round): IST is 3 hours 30 minutes behind (constant). IST vs AEST (Sydney, winter): IST is 4 hours 30 minutes behind. IST vs AEDT (Sydney, summer): IST is 5 hours 30 minutes behind. Use the converter above for any specific time — these are offsets, not direct time lookups.
Can I convert time for a past or future date?
Yes. Change the date field to any date — past or future — and the converter applies the correct timezone offset and DST rules for that specific date. This is particularly useful for: Planning future international meetings — check if your proposed call time falls during DST or standard time in the other country, as the offset can differ by an hour. Verifying past event times — confirm what local time a live stream, match, or conference was in your timezone. Checking seasonal offsets — see that a regular 3:00 PM IST call corresponds to 10:30 AM London in summer but 9:30 AM London in winter. Flight itinerary planning — enter your departure or arrival time to verify local time at the destination. Legal and contractual deadlines — confirm what midnight UTC (a common contract deadline) corresponds to in IST for a specific future date.
How many timezones are supported and which ones?
The converter's dropdown includes 60+ carefully selected major timezones covering all inhabited regions, including: Asia: Kolkata (IST), Dubai, Karachi, Dhaka, Colombo, Kathmandu (NPT, UTC+5:45 — a 45-minute offset), Kabul (AFT, UTC+4:30 — another rare half-hour offset), Tashkent, Almaty, Shanghai, Tokyo, Seoul, Singapore, Bangkok, Jakarta, Manila, Rangoon, Baghdad, Tehran, Riyadh, Jerusalem, Muscat. Europe: London, Paris, Berlin, Rome, Amsterdam, Madrid, Moscow, Istanbul, Athens, Warsaw, Stockholm, Zurich. Africa: Cairo, Johannesburg, Lagos, Nairobi. Americas: New York, Chicago, Denver, Los Angeles, Phoenix (no DST), Anchorage, São Paulo, Mexico City, Toronto, Vancouver, Buenos Aires, Bogotá. Pacific: Auckland, Sydney, Melbourne, Perth, Honolulu, Fiji. The underlying browser IANA database covers hundreds more — these zones represent the most commonly needed conversions. If you need a specific zone not in the dropdown, the IANA zone codes for major cities are the standard reference (e.g. America/Chicago, Europe/Paris).
Why does the date change when converting some timezones?
When the time difference between two timezones is large enough, the same moment in time falls on different calendar dates in each location. This happens because the International Date Line divides the calendar — timezones west of it are "ahead" (tomorrow relative to UTC), while timezones east of it are "behind" (today or yesterday relative to UTC). Example: Monday 11:00 PM in Los Angeles (PDT, UTC-7) is the same moment as Tuesday 3:00 PM in Tokyo (JST, UTC+9) — a 16-hour difference that crosses midnight. Similarly, Sunday 9:00 AM in New York (EST) is Sunday 7:30 PM in India (IST) — still the same date. But Sunday 11:30 PM in New York (EST) is Monday 10:00 AM in India (IST) — the date has changed. This converter always shows the full date (including day of week) in both result boxes so you cannot miss this. When planning travel or international events, always verify the date column, not just the time.
What is the best time to schedule a meeting between India and the US?
Finding overlap between IST and US timezones is challenging because the gap is large — 9.5 to 13.5 hours depending on the US timezone and DST. Common workable windows: India + US East Coast (IST vs ET): The best overlap is typically 7:30–9:30 AM ET = 6:00–8:00 PM IST (summer, EDT) or 8:30–10:30 AM ET = 7:00–9:00 PM IST (winter, EST). This requires the Indian side to work into the evening and the US side to be available early morning. India + US West Coast (IST vs PT): Even harder — a 12.5–13.5 hour gap. 7:30–9:00 AM PT = 8:00–9:30 PM IST (summer) is the most common window, but requires very early mornings in SF. India + UK (IST vs GMT/BST): Comfortable overlap — 9:00 AM–1:00 PM GMT = 2:30–6:30 PM IST. The 4–5.5 hour gap is easily manageable within normal business hours for both sides. Use this converter to check any proposed meeting time: enter the time in one side's local timezone and see what it corresponds to on the other side.
Is this converter accurate for legal, financial, or contractual deadlines?
This converter provides technically accurate timezone conversions using the IANA timezone database — the same standard used by courts, financial exchanges, and governments for timestamp interpretation. However, for legal and contractual use, there are important caveats: (1) Ambiguous DST transitions: When clocks fall back (e.g. from EDT to EST in the US in November), the same local clock time occurs twice in one night. A contract deadline of "11:59 PM EST" is unambiguous, but "11:59 PM Eastern" on that specific night could mean EDT or EST. Always confirm the UTC equivalent with the other party for critical deadlines. (2) Government timezone changes: Countries occasionally change their timezone rules (e.g. Samoa switched sides of the International Date Line in 2011). The browser's IANA database is kept up to date via operating system updates, but older browsers may have stale data. (3) Jurisdiction-specific definitions: Some legal documents specify "business hours" in a timezone, which varies by region and holidays. For critical legal, financial, or contractual deadlines, always verify with the relevant party or a legal professional, and confirm the UTC equivalent explicitly.