Why payroll wants decimal, and why 8:30 is not 8.30
A clock counts sixty minutes to the hour. A pay calculation multiplies hours by a rate, and
multiplication only works in base ten. So payroll systems, and almost every timekeeping export,
store time as a decimal fraction of an hour: thirty minutes is half an hour, so
8:30 becomes 8.50. It is not 8.30. That mistake, made
once a week for a year, underpays a worker by about twenty minutes a week — seventeen hours
over the year.
The conversion is minutes divided by sixty. Forty-five minutes is 45 ÷ 60 = 0.75. Five
minutes is 5 ÷ 60 = 0.0833, which rounds to 0.08. Twenty minutes is
0.33, forty is 0.67. The awkward ones are anything not divisible by
three: seven minutes is 0.1167, which is 0.12 at two places. The chart at the
bottom of this page has all sixty.
Two decimal places is the usual precision — but check
Most payroll systems, ADP, Paychex, QuickBooks, Gusto and the like, accept two decimal places and round internally. Two places means the largest possible error on any single entry is a third of a minute, which over two weeks adds up to less than five minutes and in practice cancels out. Some systems accept four places. If yours does, the note under the converter shows the four-place figure too.
What you should not do is round to one place. 7:45 as 7.8 gives
the worker an extra three minutes; 7:20 as 7.3 takes away two. It
looks tidy and it is wrong in both directions.
Quarter-hour and tenth-hour rounding
Rounding is a different thing from conversion, and the two get confused. Conversion changes the format. Rounding changes the number.
Quarter-hour rounding snaps a time to the nearest 0.25 — so 7:52 becomes 7.75 and 7:53 becomes 8.00, because 7:53 is closer to 8:00 than to 7:45. This is the common employer practice in the United States and it is lawful under the Fair Labor Standards Act only if it rounds both ways and averages out over time. A system that rounds clock-ins up and clock-outs down is not rounding, it is taking wages.
Tenth-hour rounding snaps to the nearest six minutes — 0.1 of an hour. It is common in legal billing, healthcare and some government payroll. 7:52 becomes 7.9; 7:57 becomes 8.0.
The rounding selector at the top applies to both the single converter and the column converter, so you can see your exact hours and your rounded hours side by side and know what the rounding is costing or giving you.
Going the other way
A pay stub shows 76.42 hours for the two weeks and you want to know what that is on a clock.
Type it in the decimal box: 0.42 of an hour is 25 minutes, so 76.42 is 76:25. If
your own record says 76:35, the difference is ten minutes, and now you have a specific number
to raise rather than a feeling that something is off.
Converting a whole timesheet at once
The column converter takes one value per line. Copy a column of daily totals from your
timesheet, a spreadsheet or a text message, paste it in, and the converted column appears next
to it with the total underneath in both formats. Copy the results and paste them back into
your sheet. If a line cannot be read it comes back as ?? rather than being
dropped, so the two columns always line up row for row.
If what you have is clock-in and clock-out times rather than daily totals, this is the wrong tool — use the time card calculator, which takes the punches, handles breaks and overtime, and gives you decimal totals at the end.
Minutes to decimal chart
Every minute from one to sixty, exact to two places, and what it becomes under quarter-hour and tenth-hour rounding. Print it and keep it by the desk.
| Min | Exact | ¼ hr | ⅒ hr |
|---|
Questions people ask
Is 7.5 hours seven and a half hours or seven hours five minutes?
Seven and a half. A decimal hour is a fraction of an hour, so .5 is half an hour, thirty minutes. Seven hours five minutes would be 7.08. When someone writes 7.5 meaning 7:05 the pay stub is wrong by twenty-five minutes.
What is 0.83 hours in minutes?
Fifty minutes. Multiply the decimal part by sixty: 0.83 × 60 = 49.8, which is fifty minutes once rounded. The chart shows 50 minutes as 0.83 exactly.
Why does my payroll show 8.08 when I worked 8:05?
Because five minutes is 0.0833 of an hour and the system shows two decimal places. Nothing is missing. 8.08 hours is 8 hours and 4.8 minutes, which rounds back to 8:05.
Can I convert negative time, for a deduction?
Yes. Type -0:30 and it converts to -0.50. Useful for correcting
a previous period on a timesheet.
Does the chart change with the rounding setting?
No. The chart always shows all three columns — exact, quarter-hour and tenth-hour — so it is complete when printed. The rounding setting applies to the converters above it.