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RoomCalcs

Time calculator

Add up hours and minutes, take time away, count the hours between a start and an end time — even across midnight, minus a break — or find the clock time after a duration. Results come in hours and minutes and in decimal hours for timesheets.

  • Free
  • No sign-up
  • Private — runs in your browser

How do I add hours and minutes?

  1. 1Choose what you want: add or subtract times, hours between two times, or the time after a duration.
  2. 2Type hours, minutes and seconds, or pick clock times. Use the + / − button to subtract a time.
  3. 3Read the answer in hours and minutes, in decimal hours, and see each step.

How to calculate hours worked

  1. 01Total seconds = hours × 3,600 + minutes × 60 + seconds
  2. 02Hours worked = end − start (+ 24 h if the end is past midnight) − break
  3. 03Decimal hours = hours + minutes ÷ 60

Time doesn't add like ordinary decimals because an hour has 60 minutes, not 100. The calculator turns everything into seconds, adds or subtracts, then turns the total back into hours, minutes and seconds: 1 h 45 min + 2 h 30 min = 4 h 15 min.

For a shift, the end time minus the start time gives the time at work; if the end is earlier than the start, the shift ran past midnight, so a day (24 hours) is added. Payroll usually needs decimal hours: 7 h 45 min is 7 + 45 ÷ 60 = 7.75 hours, not 7.45.

Good to know

  • 15 minutes is 0.25 h, 30 minutes is 0.5 h and 45 minutes is 0.75 h.
  • For a weekly timesheet, add each day's hours in the first mode.
  • A night shift from 22:00 to 06:00 is 8 hours — the calculator handles the date change for you.

Time calculator — common questions

How do I add hours and minutes together?

Add the hours and the minutes separately, then turn every 60 minutes into an hour. 1 h 45 min + 2 h 30 min = 3 h 75 min = 4 h 15 min.

How do I calculate hours worked between two times?

Subtract the start time from the end time and take off any unpaid break. 09:00 to 17:30 with a 30-minute break is 8 hours.

How do I convert minutes to decimal hours?

Divide the minutes by 60. 45 minutes is 0.75 hours, so 7 h 45 min is 7.75 hours on a timesheet.

How do I calculate an overnight shift?

If the end time is earlier than the start, add 24 hours to the end time first. 22:00 to 06:00 is 30 − 22 = 8 hours.

Sources

  • Sexagesimal time arithmetic (60 seconds to a minute, 60 minutes to an hour)

Formulas last reviewed: September 30, 2026 ·How we check our formulas

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