Time Zone Converter
Convert a date and time between world time zones using real IANA zone data, so daylight saving is applied correctly rather than a fixed, half-wrong offset.
Time Zone Converter: with the default inputs, local time there is Thursday 10 September 2026, 19:30 (7:30 pm).
The date in the source zone, not in yours.
24-hour clock: 0 is midnight, 14 is 2 pm.
- Date there
- September 10, 2026
- Day change
- Same day
- Time difference
- 5Hours to add to the source zone to get the target zone.
- Source zone offset
- UTC−04:00 — EDT
- Target zone offset
- UTC+01:00 — GMT+1
- The same instant in UTC
- 2026-09-10 18:30 UTC
Assumptions
- Offsets come from the IANA time-zone database on the machine running this calculation, which is updated several times a year.
- Ambiguous local times (the repeated hour when clocks go back) resolve to the first occurrence.
- Dates are limited to 1900–2100, outside which the historical or future rules are not reliable.
| City | Local time | Local date | Offset |
|---|---|---|---|
| Los Angeles | 11:30 | 2026-09-10 | UTC−07:00 |
| New York | 14:30 | 2026-09-10 | UTC−04:00 |
| London | 19:30 | 2026-09-10 | UTC+01:00 |
| Berlin | 20:30 | 2026-09-10 | UTC+02:00 |
| Kolkata | 00:00 | 2026-09-11 | UTC+05:30 |
| Tokyo | 03:30 | 2026-09-11 | UTC+09:00 |
| Sydney | 04:30 | 2026-09-11 | UTC+10:00 |
One moment in time, seven wall clocks. Offsets are read from the IANA time-zone database for this exact date, so they already include daylight saving where it applies.
How this is worked out
The formula
A time zone is not a number; it is a rule that maps an instant to a wall clock. instant (UTC) = wall clock in the source zone − that zone's offset on that date wall clock in the target zone = instant + the target zone's offset on that date Both offsets are looked up from the IANA time-zone database for the specific date, which is why the answer changes across a daylight-saving boundary and why "New York = UTC−5" is only true from November to March.
Open How it’s calculated above to see this worked through with your own numbers.
What you enter
- Date
- The date in the source zone, not in yours.defaults to today
- Hour
- 24-hour clock: 0 is midnight, 14 is 2 pm.from 0 to 23 · whole numbers only · defaults to 14
- Minute
- A number.from 0 to 59 · whole numbers only · defaults to 30
- From zone
- Choose one of 39 options.UTC — Coordinated Universal Time · Honolulu — Hawaii · Anchorage — Alaska · Los Angeles — US Pacific · Phoenix — Arizona (no daylight saving) · Denver — US Mountain · Chicago — US Central · Mexico City · New York — US Eastern · Toronto · São Paulo · London — UK · Dublin — Ireland · Lisbon — Portugal · Paris — France · Berlin — Germany · Madrid — Spain · Athens — Greece · Istanbul — Türkiye · Moscow — Russia · Lagos — West Africa · Cairo — Egypt · Johannesburg — South Africa · Jerusalem — Israel · Dubai — UAE · Karachi — Pakistan · Kolkata / Mumbai — India (UTC+5:30) · Dhaka — Bangladesh · Bangkok — Thailand · Singapore · Shanghai / Beijing — China · Hong Kong · Seoul — South Korea · Tokyo — Japan · Perth — Western Australia · Adelaide — Central Australia (UTC+9:30) · Brisbane — Queensland (no daylight saving) · Sydney — Eastern Australia · Auckland — New Zealand
- To zone
- Choose one of 39 options.UTC — Coordinated Universal Time · Honolulu — Hawaii · Anchorage — Alaska · Los Angeles — US Pacific · Phoenix — Arizona (no daylight saving) · Denver — US Mountain · Chicago — US Central · Mexico City · New York — US Eastern · Toronto · São Paulo · London — UK · Dublin — Ireland · Lisbon — Portugal · Paris — France · Berlin — Germany · Madrid — Spain · Athens — Greece · Istanbul — Türkiye · Moscow — Russia · Lagos — West Africa · Cairo — Egypt · Johannesburg — South Africa · Jerusalem — Israel · Dubai — UAE · Karachi — Pakistan · Kolkata / Mumbai — India (UTC+5:30) · Dhaka — Bangladesh · Bangkok — Thailand · Singapore · Shanghai / Beijing — China · Hong Kong · Seoul — South Korea · Tokyo — Japan · Perth — Western Australia · Adelaide — Central Australia (UTC+9:30) · Brisbane — Queensland (no daylight saving) · Sydney — Eastern Australia · Auckland — New Zealand
What you get back
- Local time theremain answer
- Date there
- Day change
- Time difference
- Hours to add to the source zone to get the target zone.
- Source zone offset
- Target zone offset
- The same instant in UTC
What this assumes
- Offsets come from the IANA time-zone database on the machine running this calculation, which is updated several times a year.
- Ambiguous local times (the repeated hour when clocks go back) resolve to the first occurrence.
- Dates are limited to 1900–2100, outside which the historical or future rules are not reliable.
About this calculator
Enter a date and time in one place and read it in another. The conversion uses IANA zone identifiers — America/New_York, not "EST" — and asks the platform's own time-zone database for the offset on that specific date, which is the only way to get daylight saving right.
Why fixed offsets are wrong
New York is UTC−5 in January and UTC−4 in July. London is UTC+0 in winter and UTC+1 in summer. The gap between them stays at five hours most of the year, but not all of it: the US changes clocks on the second Sunday in March and the EU on the last Sunday in March, so for three weeks each spring the difference is four hours, and for one week each autumn it is six. Any converter built on a hard-coded offset table gets those weeks wrong, and they are exactly the weeks when people miss meetings.
Some zones never change at all — Arizona, Queensland, most of Asia and Africa — and a few are offset by a fraction of an hour: India is UTC+5:30, Nepal UTC+5:45, parts of Australia UTC+9:30. The calculator flags those, because whole-hour mental arithmetic silently fails on them.
The two awkward hours
Twice a year, local time misbehaves, and this converter tells you rather than guessing.
The hour that does not exist. When clocks spring forward, the local clock jumps from 02:00 straight to 03:00. Ask for 02:30 that morning and there is no such moment; the calculator says so instead of inventing one.
The hour that happens twice. When clocks fall back, 01:30 comes round a second time an hour later. The calculator uses the first occurrence — the one still on daylight time — and warns you that the input was ambiguous. If it matters, use UTC.
Reading the results
The main output is the wall clock in the target zone, with the weekday and date, because the day change is the part people get wrong. The steps show the conversion the long way round — source wall clock minus its offset gives an instant in UTC, plus the target's offset gives the answer — which is the mental model worth having: UTC is the real timeline, and every local time is a label attached to it.
The comparison table shows that same instant on seven clocks around the world, which is the fastest way to find an hour that works for a distributed team.
Limits
Dates are restricted to 1900–2100. Before that, many places had no standard time at all — they used local solar time — and the historical record in the database is uneven. After it, the rules are simply unknown: daylight-saving law changes regularly, and the database is updated several times a year. Very recent legislative changes depend on your device or this server having an up-to-date copy of that database.
Frequently asked questions
▸Why use zone names like America/New_York instead of EST?
Because EST means UTC−5 all year, and New York is only on EST for four months. The IANA name carries the whole rule — including when the clocks change and every historical change before that.
▸What happens if I enter a time that daylight saving skipped?
The calculator refuses and says why. When clocks spring forward, local time jumps from 02:00 to 03:00, so 02:30 that morning never occurred in that zone.
▸What about an hour that happens twice?
When clocks fall back, the calculator uses the first occurrence — the one still on summer time — and warns that the input was ambiguous. Booking anything in that hour is best done in UTC.
▸Why is the difference between two zones not a whole number of hours?
Several zones use half- or quarter-hour offsets. India is UTC+5:30, Nepal UTC+5:45, Adelaide UTC+9:30 and Chatham Islands UTC+12:45.
▸Are the daylight-saving rules always up to date?
They are as current as the time-zone database on the machine running the calculation. Governments change the rules with little notice — several countries did so in the last few years — so check anything more than a few months ahead.
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