Date & Time Difference Calculator
Calculate exact elapsed time between two dates, times and time zones. Uses IANA time zones and accounts for UTC offset and DST changes.
Compare full timestamps across time zones
Calculate exact elapsed time using browser-supported IANA timezone rules.
Timezone-aware duration
A clock time only has an exact global meaning when its timezone is known. DateTimeWise converts each local date and time to an instant and then measures the elapsed duration. This means UTC offsets and daylight-saving changes are reflected in the result when the browser's timezone database supports them.
Why this matters
A nine-hour-looking difference on two local clocks may represent eight or ten real hours around a daylight-saving transition. It can also differ when the start and end are in different regions.
Useful for
International project coordination, travel planning, event timing, system logs and any situation where two timestamps use different time zones. For clock times in one local day without timezone conversion, the simpler Time Duration Calculator is faster.
Elapsed time is measured between instants
Choose the time zone for each timestamp separately. For example, January 15, 2026 at 09:00 in America/New_York and January 15, 2026 at 14:00 in Europe/London represent the same instant, so the elapsed duration is zero.
In America/New_York, March 8, 2026 from 01:30 to 03:30 spans one elapsed hour because the clock moves forward. A date-only count cannot express that distinction.
Clock-change boundaries
Some local times are skipped during spring transitions and repeated during autumn transitions. This tool does not offer an explicit choice between the two occurrences of a repeated time. For those boundary cases, verify the intended UTC timestamp and calculate using UTC inputs instead. Browser timezone data may also differ with browser updates.
For calendar dates without clock times, use Days Between Dates. Read our timezone and calculation notes for limitations.