Decimal hours vs. clock time: why 7:45 isn't 7.45

Clock time is base 60: there are 60 minutes in an hour. Decimal time is base 10: there are 100 hundredths in a decimal hour. They look almost identical written down, which is why this mix-up is one of the most common payroll errors.

If you worked from 9:00 to 16:45, that's 7 hours and 45 minutes - written as "7:45" on a clock. But 45 minutes is three quarters of an hour, so as a decimal it's 7.75, not 7.45. Typing "7.45" into a field that expects decimal hours quietly shaves 0.30 hours off your pay every time it happens.

Quick conversion reference

• 15 minutes = 0.25 hours
• 30 minutes = 0.5 hours
• 45 minutes = 0.75 hours

The calculator on this site always shows both formats - the HH:MM total for a quick sanity check, and the decimal total for pasting into a timesheet, invoice, or payroll system - so you never have to convert by hand.