Time calculator
Add or subtract hours, minutes and seconds, or find the clock time before or after a duration. The answer updates as you type.
Add or subtract durations
Add time to a clock time
How it's worked out
Each amount is turned into seconds, the seconds are added or subtracted, and the total is split back into hours, minutes and seconds. Working in whole seconds means there are no rounding errors, however many rows you add. Minutes and seconds can be any size: 90 minutes is carried over as 1 hour 30 minutes.
Adding: 2:45:30 + 1:30:50
- Seconds: 30 + 50 = 80 seconds, which is 1 minute 20 seconds. Write 20, carry 1 minute.
- Minutes: 45 + 30 + 1 carried = 76 minutes, which is 1 hour 16 minutes. Write 16, carry 1 hour.
- Hours: 2 + 1 + 1 carried = 4 hours. The total is 4:16:20, or 4.27 decimal hours.
Subtracting: 1:20:00 − 2:25:00
The second time is bigger, so the answer is negative. Take the smaller from the larger: 2:25:00 − 1:20:00 = 1:05:00, then add the minus sign: −1:05:00. When you need to borrow, turn one hour into 60 minutes: 5:10 − 2:45 becomes 4:70 − 2:45 = 2:25.
Clock time: 9:30 PM + 3 hours 45 minutes
On a 24-hour clock 9:30 PM is 21:30. Adding 3:45 gives 25:15. Anything past 24:00 rolls into the next day, so take away 24 hours: 1:15 AM the next day. Subtracting past midnight works the same way in reverse and lands on the previous day.
Clock results assume a normal 24-hour day. On the night the clocks change for daylight saving time, the real elapsed time is an hour more or less.
Adding times in Excel or Google Sheets
Type durations as h:mm:ss (for example 2:45:30), one per cell, then use:
Total of A2 to A6, formatted as [h]:mm:ss so it can pass 24 hours:
=SUM(A2:A6)The same total in decimal hours (format the cell as a number):
=SUM(A2:A6)*24A clock time in A2 plus 3 hours 45 minutes:
=A2+TIME(3,45,0)Spreadsheets store times as fractions of a day, which is why multiplying by 24 gives hours. The square brackets in [h] stop the hours from wrapping back to 0 after 24.
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Frequently asked questions
How do I add hours and minutes together?
Add the minutes and the hours separately, then carry every 60 minutes over as an hour. For example, 2:45 + 1:30 is 3 hours 75 minutes, and 75 minutes is 1 hour 15 minutes, so the total is 4:15. Seconds carry into minutes the same way.
How do I subtract one time from another?
Subtract the minutes and the hours separately. If there are not enough minutes, borrow an hour and add 60 to the minutes: 5:10 − 2:45 becomes 4:70 − 2:45, which is 2:25. If you take a longer time from a shorter one, the result is negative.
What happens when adding time goes past midnight?
The clock starts again at 12:00 AM and the result is on the next day. For example, 9:30 PM plus 3 hours 45 minutes is 1:15 AM the next day. Subtracting past midnight gives a time on the previous day.
How do I convert hours and minutes to decimal hours?
Divide the minutes by 60 and add them to the hours. 2 hours 15 minutes is 2 + 15 ÷ 60 = 2.25 hours, and 4 hours 20 minutes is about 4.33 hours. To go back, multiply the decimal part by 60.
How do I add up times in Excel or Google Sheets?
Enter each duration as h:mm:ss, add them with =SUM(A2:A6), and format the total as [h]:mm:ss so it keeps counting past 24 hours. Multiply by 24, as in =SUM(A2:A6)*24, to get decimal hours. Excel shows ##### for a negative time in its default date system, so subtract the smaller time from the larger one.