Time Zone Converter

Direct answer

Add the difference between the target and source UTC offsets to the source clock, then wrap the result to a 24-hour clock. IANA’s Time Zone Database records location rules and clock transitions; this calculator deliberately uses the offsets you supply for the precise instant being checked.

Variables and formula

• Source local time: a decimal hour from the source clock.
• Source and target UTC offsets: the offsets that apply at that date and time.

Target local time = Source local time + Target UTC offset - Source UTC offset

Reproducible example

For 09:00 at UTC-4 and a target offset of UTC+1, the offset difference is 1 - (-4) = 5 hours. The target time is 9 + 5 = 14:00 on the same local date.

Interpretation

The day-shift result shows whether the chosen offsets cross a local midnight. It is a clock conversion, not a timezone lookup or an appointment decision.

Assumptions and limitations

• Both offsets apply at the same instant.
• The local time uses a decimal 24-hour clock.
• Daylight-saving changes, historical corrections and location-specific rules are not looked up.

Common mistakes

• Entering a city name when the calculator requires the offset in force on the date.
• Reversing the source and target offsets.
• Using a current offset for a meeting after a daylight-saving transition.

Assumptions

• Both entered offsets apply at the exact instant being converted.
• The entered clock is a decimal 24-hour local time.
• This calculator does not look up location rules, daylight-saving transitions, historic offsets or meeting availability.

Sources and methodology

CalcMotive publishes the formula and assumptions so you can decide whether the estimate fits your use case. See our methodology standards.

• Time Zone Database; Internet Assigned Numbers Authority; accessed Aug 13, 2026