Guide
What Is Decimal Time?
Two very different things share the name. On a timesheet, decimal time is ordinary hours written with a fraction. In 1793, it was a plan to give the day ten hours.
- Reading time3 min
- UpdatedSeptember 15, 2026
- Sections5
Decimal time on a timesheet
In payroll, time-tracking software and invoicing, decimal time means a duration written as hours with a decimal fraction. Seven and a half hours is 7.5, not 7:30. The whole hours stay as they are; only the minutes are re-expressed, as a share of the 60 minutes in an hour. The minutes to decimal converter does that single step for any number of minutes.
The reason the format exists is arithmetic. A wage is a rate per hour, and a rate can only be multiplied by a number. 7:30 is not a number, 7.5 is. The same is true of adding: three shifts of 7:30 need the minutes carried into hours by hand, while 7.5 + 7.5 + 7.5 is just 22.5.
Hundredths and tenths
Because a decimal hour is a base-10 fraction of a base-60 unit, most minute counts do not come out even. Systems therefore pick a precision and round to it:
| Scale | One step equals | Where it is used |
|---|---|---|
| Hundredths (0.01 h) | 36 seconds | Most time clocks and payroll exports; US Postal Service clock rings |
| Tenths (0.1 h) | 6 minutes | Systems that round punches to six-minute steps |
| Quarters (0.25 h) | 15 minutes | Quarter-hour rounding of start and stop times |
Hundredths is the default: it is the precision a two-decimal field holds, and it is what the Postal Service means when its timekeeping guidance says clock rings are recorded in hundredths of an hour. The payroll time clock conversion page compares the three scales for every minute of the hour.
What a decimal clock is
On a time clock or timesheet app, a decimal clock is a display that shows accumulated hours as a decimal, 8.27 rather than 8:16. It is still an ordinary 24-hour, 60-minute clock underneath; only the total is shown in decimal form so it can go straight to payroll.
Historically a decimal clock was something else entirely: a clock face with ten hours on it.
The French decimal day of 1793
The National Convention's decree on the Republican calendar, dated 4 Frimaire of Year II (24 November 1793), added a decimal division of the day. Its Article XI reads: “The day, from midnight to midnight, is divided into ten parts, or hours, every part into ten others and so on until the smallest measurable duration,” and the article was to take effect from the first of Vendémiaire, Year III.
A decimal hour of that kind lasted 144 of our minutes, and a hundredth of it, the decimal minute, 86.4 of our seconds. It is this ten-hour system, not payroll hours, that “decimal time” means in its historical sense, which is why a search for the phrase turns up both.
Reading decimal time back into clock time
A decimal total is easy to read once you know the fraction is a share of 60 minutes: 0.5 is 30 minutes, 0.25 is 15, 0.75 is 45. Anything else, multiply by 60. The decimal to hours and minutes converter gives the h:mm form, and the decimal to minutes chart lists every hundredth.