How it works
Enter a duration per row
Type hours, minutes, and seconds for each time span you want to combine.
Switch a row to subtract
Click the +/− toggle next to any row after the first to subtract it instead.
Read the total instantly
The combined duration and its decimal-hours equivalent update as you type.
Time Calculator adds and subtracts a list of durations expressed as hours, minutes, and seconds — the kind of arithmetic that comes up when tallying overtime across several shifts, combining multiple recorded intervals, or figuring out how much time is left after subtracting one span from another.
Each row contributes a signed number of seconds to a running total; rows after the first can be flipped to subtract instead of add. The total is converted back into hours/minutes/seconds (rolling into a day count once it passes 24 hours) and also shown as decimal hours, since payroll and billing systems typically want "1.5 hours" rather than "1 hour 30 minutes."
Because durations aren't tied to a calendar or timezone the way dates are, the arithmetic here is pure base-60/24 carrying — no leap years, no daylight saving shifts, just seconds added up and re-split into larger units.