Time Duration Calculator
Find the exact elapsed time between two moments, each in its own timezone — useful for flights, remote meetings, and cross-timezone shifts.
Example: A flight departing New York at 9:00 PM EST on a Friday and landing in London at 8:00 AM GMT on Saturday has an elapsed duration of 7 hours — even though the local clock times appear to span 11 hours, because the 5-hour timezone difference accounts for the gap.
Accounts for timezone offset and DST transitions between the two datetimes, not just a flat subtraction.
How the duration is calculated
Because the start and end datetimes can each carry their own timezone, both are first normalised to a common reference before the difference is computed — essential when the two events genuinely happened in different places, such as a flight's departure and arrival, or two log entries from servers in different regions. The exact elapsed time is then broken down into years, months, weeks, days, hours, minutes, and seconds, alongside a simple Monday–Friday working-days count.
If both your start and end datetime share the same timezone and you don't need the time-of-day precision, the simpler Date Difference Calculator covers that case directly. To count down to a future datetime that updates live rather than compute a duration between two fixed points, see the Countdown Timer.
Frequently asked questions
- How is this different from a plain date difference calculator?
- This one includes the time of day and lets the start and end each be in a different timezone — useful for flight durations, cross-timezone project timelines, or exact elapsed time between two logged events.
- What counts as a "working day"?
- A simple Monday-Friday count between the two dates, with no public-holiday calendar — pure calendar math, not a business-days lookup.
- What if the end is before the start?
- The duration is still calculated as a positive magnitude, with isNegative flagged true so you know the order was reversed.
- How is the duration calculated?
- Both the start and end datetime are first converted to a common reference (UTC) using their respective timezones, then the exact elapsed time between the two is computed and broken down into years, months, weeks, days, hours, minutes, and seconds — plus a separate working-days count.
- Does this account for daylight saving time?
- Yes — because each datetime is anchored to a specific IANA timezone rather than a fixed UTC offset, any daylight saving transition that falls between the start and end is correctly reflected in the elapsed duration.
- What is the difference between duration in hours and in business hours?
- This calculator reports total elapsed calendar duration (including nights, weekends, and holidays) and a separate simple working-days count (Monday–Friday only). It does not compute a "business hours only" duration that excludes non-working hours within each day — for that level of granularity, you would need to calculate it manually from the working-days figure.
- How precise is the calculation?
- Down to the second, based on the exact date, time, and timezone you enter for both the start and end — there is no rounding beyond the seconds figure in the breakdown.