Timezone Converter
Pick a source timezone, date, and time — see the result in up to ten target zones instantly. DST handled automatically.
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→ / ← to move · ↑↓ to adjust
→ / ← to move · ↑↓ to adjust
How Time Zone Conversion Works
Every point in time can be expressed as a single UTC (Coordinated Universal Time) value — a universal reference point. A timezone converter works by first converting the source local time to UTC, then converting that UTC value to each target timezone's local time. The conversion formula involves the timezone's current UTC offset, which may vary throughout the year due to Daylight Saving Time.
This converter uses your browser's built-in Intl.DateTimeFormat API, which in turn uses the IANA timezone database. The IANA database is updated several times per year as countries announce DST rule changes, and browsers stay current through OS and browser updates. This means the conversions here reflect real-world DST rules for the specific date you enter — not just a fixed offset.
Standard vs. Daylight Saving Time
Many countries shift their clocks forward by one hour in spring ("spring forward") and back by one hour in autumn ("fall back"), adding an hour of daylight to the evening at the cost of darker mornings. This practice is called Daylight Saving Time (DST) or Summer Time in European countries.
The US transitions from EST (UTC-5) to EDT (UTC-4) on the second Sunday of March, and back on the first Sunday of November. The UK transitions from GMT (UTC+0) to BST (UTC+1) on the last Sunday of March, and back on the last Sunday of October. Crucially, these transitions happen on different dates, so for a few weeks each spring and autumn the US-to-UK offset temporarily changes by one hour.
Not all regions observe DST. Arizona (except the Navajo Nation), Hawaii, and most of the tropics and southern hemisphere countries near the equator do not shift their clocks. Japan, China, India, and much of Southeast Asia also remain on fixed offsets year-round.
Common Time Zone Pairs
New York ↔ London: Normally 5 hours ahead (EST to GMT) or 4 hours (EDT to BST). For 2–3 weeks in March and October when one region has switched and the other has not, the difference is either 4 or 5 hours.
New York ↔ Los Angeles: Always exactly 3 hours behind (PT is 3 hours behind ET), because both follow US DST rules on the same schedule.
London ↔ Tokyo: Japan is UTC+9, UK is UTC+0 or UTC+1. The difference is 9 hours in winter and 8 hours in summer.
New York ↔ Mumbai: India Standard Time (IST) is UTC+5:30. EST is UTC-5, so the difference is 10.5 hours in winter (IST is 10h30m ahead). During EDT, the difference is 9.5 hours.
Eastern ↔ Central: Central Time is always exactly 1 hour behind Eastern Time. Both follow the same US DST schedule, transitioning on the same dates. When it's noon in New York (ET), it's 11:00 AM in Chicago (CT).
UTC ↔ IST (India): India Standard Time is fixed at UTC+5:30 year-round — India does not observe DST. A 9:00 AM UTC meeting is 2:30 PM IST.
Frequently Asked Questions
How do I convert time between time zones?
Select the source timezone, date, and time above. The converted times appear instantly in your chosen target zones. The converter uses the actual DST-adjusted offset for the date you enter, so results are correct across DST transitions.
How do I convert EST to PST?
Click the "EST → PST" preset button above, or manually select America/New_York as the source timezone and America/Los_Angeles as the target. Eastern Time is always exactly 3 hours ahead of Pacific Time. Both zones follow the same US DST schedule, so the 3-hour difference is constant year-round. 12:00 PM EST = 9:00 AM PST.
How do I convert UTC to EST?
Click the "UTC → EST" preset or select UTC as your source and America/New_York as the target. During standard time (November–March), EST is UTC-5 — subtract 5 hours. During Daylight Saving Time (March–November), Eastern becomes EDT at UTC-4 — subtract 4 hours. This converter applies the correct offset automatically based on the date you enter.
What is the time difference between EST and PST?
EST (UTC-5) is always three hours ahead of PST (UTC-8). During summer, both shift to EDT (UTC-4) and PDT (UTC-7), maintaining the three-hour difference. 9:00 AM EST = 6:00 AM PST.
Why does my timezone converter show the wrong time?
Most often this is a DST issue. The offset changes on specific dates each year. This converter uses the IANA timezone database to apply the correct DST-adjusted offset for the specific date you enter.
How many time zones are there?
24 standard hour-based zones, but about 38 distinct UTC offsets in practice because some regions use 30-minute or 45-minute offsets (India: UTC+5:30, Nepal: UTC+5:45, Iran: UTC+3:30). The IANA database contains over 400 named timezone designations.
What is the IANA timezone database?
The IANA tz database is the authoritative reference for world timezones, updated several times per year as countries change their DST rules. It uses Region/City names (America/New_York, Europe/London). All major operating systems, browsers, and programming languages use this database.