Time Calculator
Add or subtract hours and minutes from any time, or find the exact duration between two times.
Add or Subtract Time
Time Duration Calculator
About This Time Calculator
This free time calculator handles two common needs: adding or subtracting a duration from a starting time, and computing the exact length of time between two points. Both calculations correctly handle midnight rollovers, so adding hours past 24:00 or subtracting hours before 00:00 always returns the accurate result with day adjustments noted.
Common uses include calculating work shift lengths, figuring out what time a task will finish if started now, billing hourly work, and converting between 12-hour and 24-hour time arithmetic without manual calculation errors.
Time Calculator — Frequently Asked Questions
A time calculator lets you add or subtract hours, minutes, and seconds from a starting time, or calculate the exact duration between two times. It is commonly used for shift scheduling, billing hours, cooking timers, project deadlines, and any task involving time arithmetic that is error-prone to do by hand.
Enter your starting time, then enter the number of hours and minutes you want to add. The calculator instantly returns the resulting time, automatically handling rollovers past midnight (e.g. adding 5 hours to 9:00 PM correctly returns 2:00 AM the next day).
Enter a start time and an end time. The calculator computes the total duration in hours and minutes. If the end time is earlier than the start time, it assumes the duration spans into the next day.
Yes. Subtracting more time than is available before midnight correctly rolls back to the previous day — for example, subtracting 3 hours from 1:00 AM returns 10:00 PM the previous day.