Why Payroll Runs on Decimal Hours
Clocks count in 60s, money counts in 100s — and every timesheet lives in the crack between the two. '7 hours 24 minutes' can't be multiplied by an hourly rate until the minutes become a fraction of an hour, and the classic payroll error is typing 7.24 instead of the correct 7.40: on a $20 rate that underpays $3.20, every single shift.
This calculator converts both directions — time to decimal for payroll and invoicing, decimal back to hours and minutes for reading timesheet exports — and shows the quarter-hour and tenth-hour roundings that real timekeeping systems apply.
Working with decimal numbers more generally — rounding, fractions, place value? That's our Decimal Calculator.
How to Convert Hours to Decimal Hours
One division each way:
Decimal hours = hours + (minutes ÷ 60) Minutes = decimal fraction × 60
Worked both ways: 3:45 → 3 + 45÷60 = 3.75 decimal hours. And 6.42 decimal hours → 6 hours + 0.42×60 ≈ 6:25. The mistake to avoid: the digits after the colon are minutes (out of 60), the digits after the decimal point are hundredths of an hour — 7:30 and 7.30 are eighteen minutes apart.
Hours to Decimal Chart: Every Minute Value
The conversions worth memorizing — every timesheet reduces to these:
| Minutes | Decimal hours | Common name |
|---|---|---|
| 6 min | 0.10 | A tenth |
| 15 min | 0.25 | Quarter hour |
| 20 min | 0.33 | |
| 30 min | 0.50 | Half hour |
| 36 min | 0.60 | |
| 45 min | 0.75 | Three quarters |
| 48 min | 0.80 | |
| 60 min | 1.00 | Full hour |
The two clean systems hiding in this chart: every 6 minutes is exactly 0.10 hours (the 'tenths' system), and every 15 minutes is exactly 0.25 (the 'quarters' system). If your employer's timesheet shows numbers like 7.10 and 7.20, they're on tenths; 7.25 and 7.75 means quarters.
Payroll Rounding: Quarter Hours and Tenths
Most timekeeping systems don't pay raw minutes — they round to the nearest quarter hour (15 minutes) or tenth of an hour (6 minutes). Under the widely used quarter-hour convention, clocking in at 8:53–9:07 books as 9:00: roughly, up to 7 minutes rounds down and 8 or more rounds up. Over a pay period the rounding is designed to average out in both directions.
What's worth checking on your own paystub: rounding must be applied neutrally, not always in the employer's favor — systematic down-only rounding is the classic wage-theft pattern. This calculator's quarter-hour and tenth-hour outputs let you verify what a fair rounding of your actual time should look like.