Durations convert to seconds, combine, then split back into h:m:s. Time 2 minus Time 1 clamps at zero. For time spans that cross midnight, end < start is assumed to be the next day. Related: hours, time difference, timezone.
The add/subtract mode converts each time into total seconds, performs the arithmetic, then splits the result back into hours, minutes, and seconds. The clock-time mode converts start and end times to minutes since midnight, subtracts, and wraps across midnight if needed. Decimal hours are simply total minutes divided by 60.
The result is clamped at 00:00:00. This calculator does not display negative durations — if you need the absolute difference regardless of order, swap the two inputs.
If the end time is earlier than the start time (for example, 11:00 PM to 2:00 AM), the tool assumes you crossed midnight and adds 24 hours to the end time before subtracting. This gives you the forward-looking duration.
Many payroll, billing, and project-tracking systems require time in decimal form. For example, 7 hours and 45 minutes is entered as 7.75 hours. This format simplifies multiplication by hourly rates.
Not in a single operation. To add three or more durations, compute the first two, note the result, then use that result as Time 1 and enter the next duration as Time 2.
Estimate only. Results reflect your inputs and standard formulas. Double-check important decisions independently.