Convert hours:minutes into decimal hours for payroll and timesheets (8:30 = 8.5), or decimal hours back to H:MM.
Time • payroll
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Payroll and timesheets need hours as decimals: 8 hours 30 minutes is 8.5 hours, because minutes are divided by 60. Converting H:MM to decimal hours (and back) is essential for billing, paychecks and tracking work time.
This tool converts a clock-style duration to decimal hours and decimal hours back to H:MM — handy for hourly workers, freelancers and managers reconciling timesheets.
Payroll, billing and project systems work in decimal hours while clocks work in base 60, and converting between them is the most common arithmetic error in timekeeping. Forty-five minutes is 0.75 hours, not 0.45; fifteen minutes is 0.25, not 0.15. The two coincide only at zero and at the full hour, so every intermediate value read directly is wrong. Rounding conventions add a second layer: many employers round to the nearest quarter hour, and US wage law permits that only if the rounding is neutral over time rather than consistently favouring the employer.
Decimal hours = hours + (minutes ÷ 60)Minutes = (decimal hours − whole hours) × 60Quarter-hour rounding: round(decimal × 4) ÷ 4where:
Assumptions: Rounding to the nearest quarter hour can shift up to 7 minutes per entry in either direction. Over a fortnight that is material, which is why the neutrality requirement exists.
Convert a shift length both ways, and show what the naive reading costs.
Result7 h 45 m = 7.75 decimal hours ($217.00)
Across 250 shifts a year that $8.40 error compounds to $2,100. The three values worth committing to memory are 15 min = 0.25, 30 min = 0.50 and 45 min = 0.75; everything else follows from dividing by 60.
Decimal hours and clock time look confusingly alike in writing, and the gap between them is real money. Eight hours thirty minutes is 8.5 decimal hours, not 8.30; read the wrong way, that is an error of twelve minutes on a single shift. Payroll systems, invoicing tools and spreadsheets almost all expect decimals, while the timesheet a person fills in almost always uses the colon, and the conversion between them is where the mistakes accumulate.
Rounding rules then add a second layer that is not arithmetic at all but policy. Many employers round recorded time to the nearest quarter hour, which is lawful in the United States only where the rounding is neutral over time rather than consistently in the employer's favour — the familiar seven-minute convention exists to make it symmetrical. A converted decimal figure is exact; what happens to it afterwards is a rule that should be written down rather than inferred.
The reason any of this is awkward is that timekeeping is the last widely used sexagesimal system, inherited from Babylonian arithmetic and preserved because sixty divides evenly so many ways. That is a genuine advantage when splitting an hour by thirds or quarters and a genuine nuisance when adding a column of durations, which is exactly why decimal hours exist alongside it rather than replacing it.