Time calculator

Add or subtract hours, minutes and seconds line by line, then multiply or divide the total. See the result as h:mm:ss, seconds and decimal hours.

Time values

OperationHoursMinutesSecondsRunning totalRemove row
1:45:30
4:06:15
3:36:00
Result
3:36:00
Total seconds
12,960
Decimal hours
3.6

Multiply or divide the total

Scaled result: 7:12:00

The form works in your browser; nothing you type is sent to a server.

How it is calculated

Every row is converted to seconds (hours × 3600 + minutes × 60 + seconds), added or subtracted in order, and the total is converted back to hours, minutes and seconds. Hours are not wrapped at 24, so 25:30:00 means 25 hours and 30 minutes. Fields accept overflow and decimals: 90 minutes is 1:30:00 and 1.5 hours is also 1:30:00.

Worked example: 1:45:30 + 2:20:45 − 0:30:15 = 3:36:00, which is 12,960 seconds or 3.6 hours.

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Frequently asked questions

How do I add hours and minutes together?

Convert both values to minutes, add them, then divide by 60: the whole part is the hours and the remainder is the minutes. For example 2:45 + 1:30 = 165 + 90 = 255 minutes = 4 hours 15 minutes.

What happens when the result is negative?

If you subtract more time than you added, the total is shown with a minus sign, for example −0:15:00. The decimal hours and total seconds are negative too.

How do I convert minutes to decimal hours?

Divide the minutes by 60. 15 minutes is 0.25 hours, 30 minutes is 0.5 hours and 45 minutes is 0.75 hours, so 7:45 is 7.75 decimal hours.

Can I multiply a duration, such as a lap time by 12?

Yes. Enter the duration, then use Multiply with the number 12. Divide works the same way, for example splitting a 3-hour job into 4 equal parts gives 0:45:00 each.