Date & Time
Hours to Decimal Converter
Convert hours and minutes (HH:MM) to decimal hours and back. Built for payroll timesheets, with 0 to 4 decimal places and optional seconds output.
Convert hours and decimal hours
Use the format H:MM or HH:MM. Minutes must be 00 to 59.
Decimal hours
Result
8.5
8 h 30 min equals 8.5 decimal hours.
Total minutes
510
Hours part
8 h 30 min
Frequently Asked Questions about the Hours to Decimal Converter
Why do payroll systems use decimal hours instead of HH:MM?
Payroll, accounting, and timesheet software multiply hours by an hourly rate, and that math only works in decimal form. 7 hours 30 minutes times $20 per hour is easy to compute as 7.5 times 20 equals $150, but trying to multiply 7:30 by 20 directly gives you nonsense unless you convert first. Most US payroll systems (ADP, Gusto, QuickBooks Time, Paychex) store and export hours as decimal numbers for the same reason.
How do I convert minutes to a decimal?
Divide the minutes by 60. That is the whole rule. 15 minutes is 15 divided by 60, which is 0.25. 30 minutes is 0.5. 45 minutes is 0.75. 10 minutes is about 0.17. So 8 hours 15 minutes becomes 8.25 hours, 8 hours 30 minutes becomes 8.5 hours, and 8 hours 45 minutes becomes 8.75 hours. The calculator does this conversion in both directions.
Why is doing math on hours and minutes so error-prone?
Because minutes count to 60, not 100. When you add 6:45 plus 2:30 in your head you have to track two carries: the 45 plus 30 overflows past 60, so you carry one hour and keep 15 minutes, then add the hours to get 9:15. Spreadsheets and calculators do not handle that natively unless you store the value as a true time type. Converting to decimal hours sidesteps the carry entirely and lets you use ordinary addition, subtraction, and multiplication.
What rounding rules do payroll systems usually apply?
Three rules are common in US payroll. The 5-minute rule rounds time clock entries to the nearest 5-minute mark. The 6-minute rule (one tenth of an hour) rounds to the nearest 0.1 hours, which is how most ADP and QuickBooks Time exports are tuned. The 15-minute rule (the so-called 7/8 rule) rounds to the nearest quarter hour, with 8 minutes as the cutoff. Under the federal Fair Labor Standards Act, rounding is allowed as long as it does not systematically shortchange the employee over time.
How can I keep my decimal hours accurate?
Three tips. First, decide your rounding convention up front (2 decimals is the safe default for payroll, 4 decimals is overkill for almost everything). Second, do all your addition in minutes or in decimal hours, never mix the two midway through. Third, when you convert back from decimal hours to HH:MM, accept that 8.33 hours rounds to 08:20 (8 hours 19.8 minutes rounded up), not 08:33. Use the seconds option above if you need to see the exact remainder.