Time Zone Converter

What this calculator does

This time zone converter takes a date and time in one time zone and shows the equivalent moment in another. You choose a date, a time, a source zone and a target zone from a curated list of common locations, and the tool displays the converted local time along with the UTC offset of both zones. The source zone defaults to the one your browser reports, because converting from your own time is the usual starting point. Results recalculate the instant you change any field, a swap button flips the two zones, and the converted time has a one-click copy button.

Why you might need it

Coordinating across time zones is a constant source of confusion and missed meetings. You might be scheduling a call with colleagues on another continent, catching a livestream announced in a foreign zone, planning travel across several regions, or working out when a deadline set in UTC falls in your local day. Daylight saving makes mental conversion even harder, because the gap between two zones can change twice a year. Seeing both local times and both UTC offsets side by side removes the ambiguity and lets you confirm a time at a glance.

How to use it

1. Set the date and time of the event in the source zone.
2. Choose the from time zone — it defaults to your own location.
3. Choose the to time zone you want the time converted into.
4. Read the converted time headline and the offset shown beneath it.
5. Compare the Source and Target panels to see both zones together. Use Swap zones to reverse the direction or Reset to return to defaults.

How it’s calculated

The converter never moves a clock by a fixed number of hours, because that would break whenever daylight saving differs between the two zones. Instead it works with a single absolute instant in time. The wall-clock date and time you enter are interpreted in the source zone to find the exact universal instant they correspond to, correcting for that zone’s offset on that date. That same instant is then formatted in the target zone using the browser’s Intl date functions, which consult the IANA time zone database for the correct rules. The UTC offset for each zone is derived by comparing the zone’s formatted wall clock with the underlying instant, so it always reflects the offset in force on the chosen date.

Common pitfalls

The most common mistake is assuming the difference between two zones is fixed. Many regions observe daylight saving, and they do not all switch on the same date, so the gap between, say, London and New York is not constant through the year — always convert for the specific date. A second pitfall involves the brief windows around a clock change: when clocks spring forward an hour of wall-clock time does not exist, and when they fall back an hour repeats, so a time inside those windows is genuinely ambiguous. Finally, remember that abbreviations like “CST” are reused by different regions; the curated zone list avoids that by naming a city for each entry.

Tips and related calculations

When inviting people across zones, share the time together with its UTC offset, or state it in UTC, so there is no room for misreading. Use the swap button to quickly check a time in both directions. If you need the number of days between two dates rather than a clock conversion, a date difference calculator is the right tool, and a date add-and-subtract calculator handles shifting a date by a fixed span. Because every conversion here runs locally using your browser’s own time zone data, you can compare as many moments as you like, and none of the details ever leave your device.