Time zone converter

Pick a date, a time and two time zones. Daylight saving time is handled for the exact date you choose.

By the Calcist team · Checked against known answers · Updated October 27, 2026

Private: calculated on your device. Nothing you type is sent anywhere.

Next: Planning how long until the meeting date? Use days between dates, or add up call lengths with the time calculator.

How the conversion works

UTC time = local time − that zone's UTC offset on that date
Target time = UTC time + the target zone's offset on that date

The offsets come from your browser's built-in copy of the IANA time zone database (through JavaScript's Intl API). It holds every zone's rules, including when daylight saving starts and ends, so a time in July uses summer time and a time in January doesn't. Nothing is looked up online.

Worked example

Noon on July 1, 2026 in New York is in Eastern Daylight Time, UTC−4, so it's 4:00 PM UTC. London is on British Summer Time, UTC+1, so the meeting is at 5:00 PM there. In January both cities are on standard time (UTC−5 and UTC+0) and the gap is still 5 hours, but for a few weeks in March and in late October/early November it's only 4, because the US and the UK change their clocks on different dates.

Times that happen twice, or not at all

Spring forward: on March 8, 2026, US clocks jump from 2:00 AM to 3:00 AM, so 2:30 AM doesn't exist. It's read as 3:30 AM daylight time, an hour later.
Fall back: on November 1, 2026, 1:00 to 2:00 AM happens twice. The calculator uses the first one (daylight time) and tells you.

US daylight saving time runs from the second Sunday in March to the first Sunday in November. Most of Arizona and all of Hawaii don't use it.

Limitations

Future rule changes. Countries sometimes change their time zone or daylight saving rules with little notice. Results follow the rules your browser knows about, so keep it updated.
Abbreviations are ambiguous. CST can mean US Central or China Standard Time, and IST can mean India, Israel or Irish time. Typed US abbreviations (EST, CST, MST, PST) are read as the US zones; for anywhere else, pick a city. An abbreviation is read as its region's zone, so PST typed for a July date gives Los Angeles on PDT (UTC−7), and the result points this out. Arizona doesn't use daylight saving: type Phoenix rather than MST.
Historical dates before time zones were standardized (1883 in the US) use each city's local mean time from the database.

Sources

IANA Time Zone Database (the zone names and daylight saving history browsers use)
15 U.S. Code § 260a (US daylight saving time: second Sunday in March to first Sunday in November)
MDN: Intl.DateTimeFormat (the browser feature that applies the time zone rules)

How we checked this

Before every update, this calculator is run in a real browser with these known answers, and it must match all of them:

Noon July 1, 2026 in New York = 5:00 PM in London ✓
9:00 AM Jan 15, 2026 in India = 7:30 PM Jan 14 in Los Angeles ✓
1:30 AM Nov 1, 2026 in New York happens twice; the first is 5:30 AM UTC ✓
2:30 AM Mar 8, 2026 in New York doesn't exist (clocks skip ahead); read as 3:30 AM EDT = 7:30 AM UTC ✓
Mumbai is accepted as India time: 9:00 AM Jan 15, 2026 = 3:30 AM UTC ✓
AEST is accepted as Sydney: 9:00 AM Jul 1, 2026 = 11:00 PM UTC Jun 30 ✓
PST typed for July is flagged: Los Angeles is on PDT ✓

Last checked October 26, 2026. Spotted something wrong? The math is done in your browser with the formula shown on this page, so you can check any result by hand.

Add this calculator to your website (free)

Paste this code into any web page. The calculator works on your page, resizes itself, has no ads and no tracking, and nothing your visitors type is sent anywhere. More about embedding.

<iframe src="https://calcist.com/embed/time-zone-converter/" title="Time zone converter" width="100%" height="640" loading="lazy" style="border:0;max-width:760px"></iframe>
<p style="font:14px/1.4 sans-serif;margin:4px 0 0"><a href="https://calcist.com/time-zone-converter/">Time zone converter</a> by Calcist</p>
<script src="https://calcist.com/embed.js" async></script>

Questions people ask

What time is it in London when it's noon in New York?

Usually 5:00 PM. For a few weeks in March and in late October to early November it's 4:00 PM, because the US and UK change their clocks on different dates.

Does this handle daylight saving time?

Yes. It uses the rules for the exact date you choose, from your browser's built-in time zone database.

What's the difference between EST and EDT?

EST (UTC−5) is Eastern Standard Time in winter. EDT (UTC−4) is Eastern Daylight Time from March to November. The zone America/New_York switches between them automatically.

Is UTC the same as GMT?

For everyday use, yes: both are UTC+0. London uses GMT in winter but BST (UTC+1) in summer, so London isn't always on UTC.

How many time zones are there?

Your browser knows over 400 named zones because each region keeps its own history of offsets and daylight saving rules, even when they share the same offset today.

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