How this calculator works
Clock units are not decimal: an hour has 60 minutes and a minute has 60 seconds. Converting to decimal hours therefore divides the minute part by 60 and the second part by 3600 before adding them to the whole hours. Decimal minutes and decimal seconds work the same way in the other direction. The table also shows each piece on its own, which is useful when only one conversion is needed.
Formula
Decimal hours = H + M/60 + S/3600. Decimal minutes = 60H + M + S/60. Decimal seconds = 3600H + 60M + S.
Worked example
7 hours 45 minutes 30 seconds is 7 + 0.75 + 0.008333 = 7.758333 decimal hours. The same span is 465.5 decimal minutes or 27930 decimal seconds.
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Frequently asked questions
Why is 45 minutes 0.75 hours?
Because 45/60 = 0.75. Dividing the minutes by 60 expresses them as a fraction of an hour, so the whole hours can simply be added in front of the decimal point.
When would I need decimal minutes?
Some billing, navigation and timing systems store minutes as a single number rather than hours and minutes. Decimal minutes keep the minutes as the unit and turn the hours into 60-minute multiples.
Can the minutes or seconds be 60?
No. The page rejects 60 or more so that the answer is not ambiguous. Write 1 hour 0 minutes instead of 0 hours 60 minutes.
Is this the same as decimal time?
No. Decimal time, such as French revolutionary time, divides the day into ten parts. This page just expresses an ordinary duration as a decimal number of hours, minutes or seconds.