Timing a task, planning a shift, or working out when an oven timer finishes? The time duration calculator does two everyday jobs: it measures the gap between two clock times, and it adds or subtracts a duration from a starting time — instantly and entirely in your browser.
Time between two times
Enter a start and an end time and the tool reports the span in hours-and-minutes, in decimal hours, and in total minutes. If the end is earlier than the start it assumes the clock crossed midnight and wraps around a 24-hour day; you can also force this with the overnight checkbox for night shifts.
Add or subtract a duration
The second panel takes a start time and a hours/minutes/seconds duration and shifts the clock forwards or backwards. When a calculation runs past the end of the day, the result wraps and shows a day-offset label so you always know which day the final time lands on.
Why decimal hours matter
Payroll, invoicing and project tracking usually expect decimal hours rather than hours-and-minutes: 7 hours 45 minutes is 7.75 hours, not 7.45. The calculator always shows the decimal form alongside the human-readable duration so you can drop the right number straight into a spreadsheet.