Time Zone Converter
Convert a date and time from one zone to another, with daylight saving handled automatically from your browser's own IANA database.
How it works
The conversion goes through UTC: your wall-clock time is resolved to an absolute instant using the source zone's rules, then rendered in the target zone. That two-step is what makes daylight saving come out right.
Offsets are read from your browser's IANA time zone database rather than a hardcoded table, so DST transitions, historical changes and政 policy updates are always current. A zone's offset is not a fixed property — New York is UTC−5 in winter and UTC−4 in summer.
This is why converting a future meeting time can surprise you: if the date falls the other side of a DST change in either zone, the gap between the two cities is not the gap you have today. The tool uses the rules that apply on the date you enter, not today's.
The formula
Conversion
target time = UTC instant rendered in the target zone
Offset
difference = target offset − source offset at that instant
Why not just add hours
offsets change with the date
DST means the gap between two cities is not constant year-round.
Worked examples
| Scenario | Working | Result |
|---|---|---|
| 09:00 London to New York | Both on DST or both off | 04:00 the same day |
| A March meeting across the DST gap | US changes before the UK | The usual gap shifts by an hour |
| India at UTC+5:30 | Half-hour offset | Not every zone is a whole hour |
When you'd use it
- Scheduling a call across countries
- Checking what time a launch or deadline lands locally
- Converting a timestamp from a colleague in another zone
- Planning around a daylight saving change
Common questions
Does this handle daylight saving?
Yes, automatically, using the rules that apply on the date you enter rather than today's. That matters for meetings booked across a DST change, where the usual gap between two cities shifts by an hour for a couple of weeks.
Why is the gap between two cities different at different times of year?
Because countries change clocks on different dates, and some do not change at all. The US and Europe switch weeks apart, so for those weeks the London-to-New-York gap is four hours rather than five.
Are all offsets whole hours?
No. India is UTC+5:30, Nepal is UTC+5:45, and parts of Australia use half-hour offsets. Assuming whole hours is a common source of scheduling errors with South Asia.