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Time Calculator

Convert hours, minutes and seconds into a total duration and into decimal hours, minutes and seconds. Useful for timesheets, video length and workout logs.

How it works Report a problem

Time Math

Algebraic time calculations

About the Time Calculator

Convert hours, minutes and seconds into a total duration and into decimal hours, minutes and seconds. Useful for timesheets, video length and workout logs.

How to use the Time Calculator

  1. Enter the Hours, Minutes and Seconds.
  2. Press Calculate to see the total in each unit.

Formula and method

Total seconds = hours × 3,600 + minutes × 60 + seconds. Decimal hours = total seconds ÷ 3,600.

Worked example

2 h 45 min 30 s = 7,200 + 2,700 + 30 = 9,930 seconds = 2.7583 hours.

Adding durations. 1 h 45 min + 2 h 30 min = 3 h 75 min, which carries over to 4 h 15 min.

When to use the Time Calculator

  • Adding and subtracting hours and minutes for timesheets.
  • Working out the total of several durations.
  • Finding the end time of a task from its start and length.

Common mistakes to avoid

  • Treating minutes like decimals. Adding 1 h 45 min and 2 h 30 min gives 4 h 15 min, not 3.75.
  • Ignoring the 60-minute limit when carrying over.

Tips

  • Timesheets often need decimal hours: 45 minutes is 0.75 hours.
  • Minutes and seconds above 59 are rolled into the next unit.

Frequently asked questions

How do I convert minutes to decimal hours?
Divide the minutes by 60. Thirty minutes is 0.5 hours.
How do I convert hours and minutes to decimal hours?
Divide the minutes by 60 and add them to the hours. 4 h 15 min = 4.25 hours.