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Time & Date

Time Calculator

Time Calculator

Add or subtract hours, minutes, and seconds. See the result as h:mm:ss, decimal hours, total minutes, and total seconds.

h
min
s
h
min
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Results appear as you type.

How to use

  1. Enter the first duration in hours, minutes, and seconds. Empty fields count as zero.
  2. Choose Add or Subtract.
  3. Enter the second duration.
  4. Read the result in h:mm:ss, plus decimal hours and total minutes.

Formula

seconds = hours × 3600 + minutes × 60 + seconds
result = first ± second (in seconds)
h:mm:ss = floor(result / 3600) : remaining minutes : remaining seconds

Worked examples

Adding two durations

2:45:30 plus 1:30:45 is 4:16:15, which is 15,375 seconds or about 4.27 hours.

Subtracting a longer time

1:15 minus 2:40 is -1:25:00. The result is negative because the second time is longer.

Going past 24 hours

20 hours plus 9 hours 5 minutes is 29:05:00, or 1 day 5:05:00.

Assumptions

  • These are durations, not clock times. To find hours between two clock times, use the Hours Calculator.
  • Minutes and seconds above 59 are allowed and carried over. 90 minutes is treated as 1:30:00.

FAQ

How do I add hours and minutes?

Convert both to minutes, add them, then divide by 60. The whole number is hours and the remainder is minutes. The calculator does this for you.

How do I convert minutes and seconds to decimal hours?

Divide total seconds by 3,600. For example 45 minutes 30 seconds is 2,730 seconds, which is 0.7583 hours.

Can the result be negative?

Yes. If you subtract a longer time from a shorter one, the result shows a minus sign.

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