How time zone conversion works
Time zones are indexed relative to Coordinated Universal Time (UTC). The offset difference between the source zone and target zone is applied to the clock time.
When the conversion passes midnight, the calculator indicates whether the converted time falls on the same day, next day or previous day.
Worked example
Converting 14:00 London time (GMT / UTC+0) to New York time (EST / UTC-5):
New York is 5 hours behind London. Subtracting 5 hours yields 09:00 (9:00 AM) on the same calendar day.
Inputs for the zone time calculator
Time to convert
The starting time in your source location in 24-hour format.
Source time zone
The time zone of the starting location.
Target time zone
The destination time zone you want to convert into.
CALCULATOR QUESTIONS
Zone time calculator questions
Does the calculator support 12-hour AM/PM format?
Yes, the results display both 24-hour notation (e.g. 14:00) and 12-hour AM/PM notation (e.g. 2:00 PM).
How do day shifts work?
If converting an evening time to a zone hours ahead moves past midnight, the tool flags that the result occurs on the next day.