Decimal hours for payroll and timesheets
How to convert hours and minutes into decimal hours, why payroll systems need it, and a quick reference for common minute-to-decimal values.
Why payroll uses decimal hours
Pay is a rate multiplied by time, and multiplication is far easier when time is a single decimal number rather than a mix of hours and minutes. Multiplying an hourly rate by 7.5 is straightforward, while multiplying by 7 hours 30 minutes invites mistakes. That is why timesheet and payroll software almost always store worked time as decimal hours. Reporting your hours in that form keeps your pay in step with the system that calculates it.
How the conversion works
To turn minutes into a decimal, divide the minutes by 60. Thirty minutes is 30 divided by 60, which is 0.5, so 7 hours 30 minutes becomes 7.5. Forty-five minutes is 0.75 and fifteen minutes is 0.25. This calculator does the division for you and rounds to two decimal places, so a 20 minute remainder shows as 0.33 rather than an endless decimal.
Watch out for rounding differences
Because some minute values do not divide evenly by 60, rounded decimals can differ from the exact minutes by a hair. Twenty minutes is 0.333 recurring, shown here as 0.33, so a week of such shifts can drift a minute or two from the sum of the exact times. When precision matters, add up the hours and minutes first and convert the weekly total once, rather than rounding each day and then summing.
A quick minute reference
A handful of values cover most timesheets. Fifteen minutes is 0.25, twenty is 0.33, thirty is 0.5, forty is 0.67, forty-five is 0.75 and fifty is 0.83. Memorizing the quarter-hour marks alone, 0.25, 0.5 and 0.75, handles the majority of standard breaks and shift lengths. For anything in between, dividing the minutes by 60 always gives the exact figure.