Time Zone Calculator
From Timezone
To Timezone
Converted Time07:00
Offset Difference-5 hours
The Time Zone Calculator converts a clock time from one zone to another by applying the difference between their UTC offsets. It supports a set of common abbreviations including UTC, GMT, EST, CST, MST, PST, CET, JST, IST, and AEST, and reports both the converted time and the raw hour offset between the two zones. It is built for quick "what time is it there" checks when scheduling calls or coordinating travel.
Formula
convertedTime = (inputTime + (offset_to − offset_from)) mod 24h
- inputTime
- Time entered in the source zone, in hours and minutes
- offset_from
- UTC offset of the source zone (e.g. EST = −5)
- offset_to
- UTC offset of the destination zone (e.g. JST = +9)
How it works
- Enter a time as HH:MM, then pick the source zone (From) and destination zone (To) from the supported abbreviations.
- The calculator looks up each zone’s UTC offset, subtracts the source offset from the destination offset, and shifts the entered time by that many hours (half-hour offsets such as IST are supported).
- Times that cross midnight wrap around the 24-hour clock, so the result is always a valid HH:MM; the offset difference is also shown.
Worked examples
A 14:30 meeting in New York (EST) needs to be expressed in Tokyo time (JST).
- EST offset is −5 and JST offset is +9, so the difference is 9 − (−5) = 14 hours.
- Add 14 hours to 14:30 → 28:30, which wraps past midnight to 04:30 the next day.
Converted time is 04:30, with an offset difference of 14 hours.
Convert 09:00 Pacific (PST) to India Standard Time (IST).
- PST offset is −8 and IST offset is +5.5, so the difference is 5.5 − (−8) = 13.5 hours.
- Add 13 hours 30 minutes to 09:00 to get 22:30.
Converted time is 22:30, with an offset difference of 13.5 hours.
Frequently asked questions
- Which time zones are supported?
- The calculator covers UTC, GMT, EST, CST, MST, PST, CET, JST, IST, and AEST. These cover most common North American, European, and Asia-Pacific scheduling needs.
- Does it account for daylight saving time?
- No. It uses fixed standard-time offsets for each zone. During local daylight saving periods (for example EDT instead of EST) you may need to adjust the result by an hour.
- How are half-hour zones like IST handled?
- India Standard Time uses a +5.5 offset, and the calculator applies the full fractional difference. Converting across IST therefore shifts the clock by a whole-and-a-half number of hours.
- What happens when a conversion crosses midnight?
- The result wraps around the 24-hour clock, so adding hours past 23:59 rolls over to the early morning, and subtracting before 00:00 rolls back to the previous evening.