What is time calculator?
Adding and subtracting time is awkward because it uses base 60 instead of base 10. Sixty minutes make an hour and sixty seconds make a minute, so ordinary calculators give wrong answers.
This calculator handles the carrying for you and also shows the total as decimal hours, minutes and seconds, which is handy for pay, billing and video work.
How to use the time calculator
- Choose add or subtract.
- Enter the first and second time.
- Read the result and the totals.
How the time calculator works
Each time is converted to seconds: days times 86,400, hours times 3,600, minutes times 60 and seconds. The tool adds or subtracts the seconds, then converts back to days, hours, minutes and seconds.
Worked example
Common uses of the time calculator
- Adding work shifts.
- Totaling video or audio lengths.
- Planning travel time.
- Billing by the hour.
- Adding race or lap times.
Tips and common mistakes
Use decimal hours when you multiply by an hourly rate.
If the result is negative, the second time was larger than the first.
Background: what to know before you rely on it
Time keeping uses base 60 because of an old system from Mesopotamia, and it still shapes our hours, minutes and seconds. Doing arithmetic in this system by hand is error prone, which is why timesheets often go wrong. The safe method is to convert everything to one unit, usually seconds or minutes, calculate, and convert back. Payroll teams then work in decimal hours, where 7 hours 30 minutes is 7.5, so conversions must be exact.
Private, free and fast
This tool runs entirely in your browser. What you type or choose is not uploaded to a server and is not saved after you close the page, which keeps it fast and private. It is free to use as often as you like. See more in all date and time tools, or browse the full list of tools.
Frequently asked questions
How do I add hours and minutes?
Add the minutes, carry every 60 into the hours and add the hours.
How do I convert minutes to decimal hours?
Divide the minutes by 60.
Can I subtract a larger time?
Yes. The result is shown as negative.
Does it handle days?
Yes.
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Results are for information and education. For legal, financial, medical or security decisions, check with a qualified professional. For legal deadlines, confirm how your contract or court counts days.