Time zone converter

Converting a time between zones is the step where scheduling goes wrong, usually because someone did the arithmetic with the wrong offset or forgot that one side had changed clocks. This tool takes a date and time in one zone and shows the same instant in as many others as you want.

Pick the source zone, enter the wall-clock time as it appears on a clock there, then read it off for every zone you have added.

How to use it

1. Set the source zone — the zone the time you have was quoted in. Use my zone fills in your own.
2. Enter the date and time as it reads on a clock in that zone. Use now fills in the current moment.
3. Add the zones you want to compare, from the shortlist or the full picker.
4. Read the result. Each row shows the local time, the local date, and how far that zone is from the source. The UTC equivalent is shown too.

Why the date matters as much as the time

A converted time frequently lands on a different calendar day. 09:00 in Tokyo on 1 March is 19:00 on 28 February in New York — a different date, a different month, and in that example a day that only exists in some years. Each row shows its own date for exactly this reason. Getting the hour right and the day wrong is the most common scheduling failure across zones.

Daylight saving, and why you should convert for the actual date

Convert for the date the event happens, not for today. Offsets change: Europe and North America both observe daylight saving but switch on different weekends, which creates short windows each spring and autumn when the usual gap between two cities is an hour off. A meeting series set up in January can shift for one side in March while the other stays put.

This tool resolves the offset for the specific date and time you enter, on both sides, so it is correct across those transitions. It also handles zones with fractional offsets, and picks a sensible reading for the hour that repeats or goes missing when clocks change.

A habit that avoids most of these problems

• Quote times with the zone attached — '14:00 UTC' or '14:00 Europe/Berlin', never a bare '14:00'.
• Prefer UTC for anything written down, like logs or schedules, and convert at the point of reading.
• Use IANA zone names such as America/New_York rather than abbreviations. EST and CST are ambiguous — CST alone maps to at least three different offsets.
• For recurring meetings, re-check the conversion after each daylight saving transition.

Frequently asked questions

Does this account for daylight saving time?

Yes, for both the source and target zones, resolved for the exact date you enter. That is why you should convert for the date the event actually happens rather than for today.

Why is the result on a different day?

Because a large enough offset pushes the same instant onto another calendar date. Each row shows its own local date so this is visible rather than assumed.

What does the UTC line mean?

It is the moment you entered, expressed in Coordinated Universal Time — the zone-independent form. Useful for putting into a log, an API call, or a message to someone whose zone you do not know.

Should I use EST or America/New_York?

Always the IANA name. EST is only correct for part of the year — the same city is EDT in summer — and abbreviations like CST are ambiguous between several countries. IANA names identify the location and let the software work out the offset.

What happens at the hour clocks change?

When clocks go forward, an hour does not exist locally; when they go back, an hour happens twice. This tool resolves such an input to a single valid instant rather than failing, but if you are scheduling inside a transition hour, pick a different time.