Hours & Minutes vs. Decimal Hours: What is the Difference?
One of the most frequent payroll and timesheet mistakes is writing 8 hours and 30 minutes as 8.3 hours. Here is why clock time and decimal payroll time are fundamentally different systems.
Clock minutes use base 60 (60 minutes per hour), while decimal numbers use base 10 (hundredths).
Because 30 minutes is one-half of an hour, 30 ÷ 60 = 0.50. Therefore, 8 hours and 30 minutes equals 8.50 decimal hours. Writing 8.30 represents 8 hours and 18 minutes (0.30 × 60), resulting in an accidental loss of 12 minutes of pay per shift.
If an employee works 8 hours and 30 minutes and you record it as 8.30 hours instead of 8.50 hours, you underpay the worker by 0.20 hours (12 minutes) every single day. Over a year, that is 50 unpaid hours of earned wages!
Base-60 (Clock Time) vs. Base-10 (Decimal Time)
Clock Time (Base 60)
Clocks measure time in sixtieths. There are 60 minutes in an hour. Half an hour is 30 minutes (30/60).
Decimal Time (Base 100)
Accounting systems measure numbers in hundredths. Half of 1.0 is 0.50. A quarter is 0.25.
Side-by-Side Comparison
| Clock Time (HH:MM) | Minutes Fraction | Decimal Equivalent | Common WRONG Entry |
|---|---|---|---|
| 15 minutes | 15 ÷ 60 | 0.25 hours | 0.15 hours |
| 30 minutes | 30 ÷ 60 | 0.50 hours | 0.30 hours |
| 45 minutes | 45 ÷ 60 | 0.75 hours | 0.45 hours |
| 60 minutes | 60 ÷ 60 | 1.00 hours | 1.00 hours |