How to convert time to decimal hours
An hour has 60 minutes, so any number of minutes becomes a decimal by dividing by 60. The hours stay as they are. 7 hours 45 minutes is 7 + 45/60 = 7.75. Going the other way, keep the whole number as hours and multiply the fraction by 60 to recover the minutes: 6.4 hours is 6 hours plus 0.4 × 60 = 24 minutes.
Payroll-friendly shortcuts
- Every 6 minutes is a tenth of an hour: 6 = 0.1, 12 = 0.2, 18 = 0.3, and so on. Systems that track in tenths round to the nearest 6-minute block.
- Every 15 minutes is a quarter: 15 = 0.25, 30 = 0.50, 45 = 0.75.
- Every 3 minutes is 0.05, which makes mental conversion quick: 21 minutes is seven blocks of 3, or 0.35.
The mistake to avoid
Writing minutes after a decimal point as if they were hundredths. 8.45 hours is 8 hours 27 minutes, not 8 hours 45 minutes. Over a 5-day week that error underpays 90 minutes. If a timesheet asks for decimal hours, use this converter or the chart above, or work the week out on the time card calculator, which shows both formats side by side.
Rounding and precision
Two decimal places can leave a rounding gap of up to 0.005 hours, which is 18 seconds and worth less than a cent at most hourly rates, so it is fine for pay. If you are summing many entries for billing, keep three places (or better, keep whole minutes) and round only the final total. Some employers round each punch to a tenth or a quarter hour instead; that is a separate rule covered under the 7-minute rule.
Tenths, hundredths, and what your timesheet expects
Two different decimal conventions are in use. Most payroll exports use hundredths (7.75), which can express any minute to within a rounding error. Some time clocks and government timesheets use tenths (7.8), which only has ten steps per hour, so they round each entry to the nearest 6 minutes first: 7 hours 45 minutes becomes 7.8 because 45 minutes is closer to 48 (0.8) than to 42 (0.7). If a form asks for tenths, convert the minutes with the chart, then round to one place. If it asks for hundredths, use two places and leave it there. Mixing the two is how 7.8 on one form quietly turns into 7 hours 48 minutes of pay on another.