Time Calculator: Add and Subtract Hours, Minutes and Seconds, and Convert Decimal Hours
Work with hours, minutes and seconds.
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How this calculator works
Choose add, subtract or convert.
Enter the hours, minutes and seconds, or the decimal hours.
The calculator gives the result as hours:minutes:seconds, in decimal hours, in minutes and in seconds.
Formulas used
- t = 3600h + 60m + s
- \text{decimal hours} = h + \frac{m}{60} + \frac{s}{3600}
Worked example
With the default numbers in the calculator above:
- Time 1 and time 2 in seconds: 9930 s and 5445 s
- The total, as hours:minutes:seconds: 4:16:15
- The result in decimal hours: 4.2708333 hours
- The result in minutes and in seconds: 256.25 minutes and 15375 seconds
Change the numbers in the calculator to see the full working, every step, for your own case.
A second worked example
A different case, with these numbers: What do you want? Subtract time 2 from time 1.
- Time 1 and time 2 in seconds: 9930 s and 5445 s
- The difference, as hours:minutes:seconds: 1:14:45
- The result in decimal hours: 1.2458333 hours
- The result in minutes and in seconds: 74.75 minutes and 4485 seconds
Common questions
How do I convert decimal hours to hours and minutes?
The whole number is the hours. Multiply the decimal part by 60 to get the minutes. 2.75 hours is 2 hours 45 minutes.
How do I add times?
Add the hours, minutes and seconds separately, then carry over any 60 seconds to a minute and any 60 minutes to an hour.
Why use decimal hours?
For pay and billing, because you can multiply decimal hours directly by an hourly rate.
Related calculators
Got a question about this? Ask an engineering question and get a plain-language answer with references.
Further reading: Basic arithmetic of time units.
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