Time Zone Converter

How it works

Enter a time, then choose the source and target zones. Both zones are shown for the same instant.

When this question comes up

Scheduling a call across continents is the obvious case, but the same arithmetic appears when you read a shipping notice, check when a market opens, or work out whether a support desk is still open. The trap is that the offset is not fixed: it moves with daylight saving, and two zones rarely switch on the same date.

Rules and limits

• Offsets come from your browser's IANA time zone database, so daylight saving is applied automatically for the current date.
• The calendar date used is today in the source zone. To compare another date, choose a zone that is already on that date.
• Nine major zones are listed; a full city search is not implemented yet.
• Around a daylight saving change, a local time that does not exist or occurs twice resolves to the nearest valid instant.

Worked example

09:00 in Shanghai (UTC+8) = 21:00 the previous day in New York during summer time (UTC−4)

Checking the result by hand

Convert to UTC first, then to the target zone. Add the source offset to reach UTC, then add the target offset. For 09:00 in Shanghai (UTC+8), UTC is 01:00; New York in summer is UTC−4, so the same instant is 21:00 the previous day. Doing it in one step is where most mistakes happen, because the date can move in either direction.

FAQ

Keep reading

• Time Zone Conversion: Five Mistakes That Cost a MeetingOffsets are not fixed, dates change more often than you expect, and daylight saving does not switch everywhere on the same day. How to convert times without getting it wrong.