WiseCalcs

Time zone converter

Enter a time and pick the source and target UTC offsets. The converter adds the difference between them and shows the time in the target zone, plus whether it falls on the same, previous, or next day.

Use it to convert a clock time from one UTC offset to another.

Converted time

21:00

Day
Same day

The result updates as you choose. The headline is the converted time; the day field shows if the conversion crosses midnight.

How does it work?

Offsets are whole hours from −12 to +14. Daylight saving time changes a zone's offset on certain dates, so check the current offset for your zones. Half-hour zones aren't covered here.

Time zone conversion

ttarget=tsource+(offsettarget−offsetsource)t_{target} = t_{source} + (\text{offset}_{target} - \text{offset}_{source})
t
Time of day in each zone.
offset
UTC offset of each zone, in hours.

15:00 at UTC−5 converted to UTC+1 adds 6 hours: 21:00 the same day. Crossing midnight shifts the date.

Method & sources

Each zone is a whole-hour UTC offset from −12 to +14. The converted time adds the difference between the two offsets. The result wraps across midnight and reports the day shift.

Sources

Where this method comes from — use these references to understand the formula, assumptions, and limits.

How we calculate

  • Each zone is a whole-hour UTC offset from −12 to +14.
  • The converted time adds the difference between the two offsets.
  • The result wraps across midnight and reports the day shift.
  • Daylight saving time and half-hour zones are not modelled.

Rounding

Times are shown as 24-hour HH:MM. The calculation uses whole minutes.

What this calculator does

Every time zone is an offset from UTC. To convert a time, you add the difference between the two offsets. This converter does that and handles the wrap across midnight, telling you when the result lands on the day before or after.

How to use it

  1. Enter the time as hour and minute.
  2. Pick the source UTC offset.
  3. Pick the target UTC offset.
  4. Read the converted time and any day shift.

A worked example

15:00 at UTC−5 to UTC+1 adds six hours, giving 21:00 the same day. Converting a late-evening time can push the result into the next day.

A note on daylight saving

Many regions shift their offset by an hour for part of the year. The converter uses the offset you pick, so check the current offset for each zone — it may differ in summer and winter.

Common mistakes

  • Using a winter offset during summer time, or vice versa.
  • Swapping the source and target offsets.
  • Forgetting the day can change when crossing midnight.

When it's useful

Scheduling a call across regions, checking when an online event starts locally, or planning around a flight's arrival time.

FAQ

How is the time converted?
The difference between the two UTC offsets is added to the source time, then wrapped within a 24-hour day.
Does it handle daylight saving time?
Not automatically. Pick the offset that's currently in effect for each zone, as it can change between summer and winter.
What does the day field mean?
Whether the converted time is the same day, the previous day, or the next day, since conversions can cross midnight.
Are half-hour time zones supported?
No. This version uses whole-hour offsets only. Some zones, like India, use a half-hour offset not covered here.
Which way do I set the offsets?
Set 'from' to the zone of the time you have and 'to' to the zone you want. The result is in the 'to' zone.
Can I share a calculation?
Yes. Use Share to copy a link that reopens the converter with the same time and offsets.

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