What this calculator does
Timesheets, payroll systems and billing software almost always work in decimal hours, where two hours and twenty minutes is 2.33 rather than 2.20. Reading a clock figure straight into a decimal field is one of the most common payroll entry errors, because 2.20 and 2.33 look similarly plausible.
The conversion is a division by 60 in one direction and a multiplication by 60 in the other. This calculator does both, and also reports the total in minutes, which is often the least ambiguous way to record a duration in the first place.
The formula
To get decimal hours, divide the minutes by 60 and add the whole hours. To go back, take the fractional part of the decimal figure and multiply it by 60 to recover the minutes.
| Term | Meaning |
|---|---|
| Decimal hours | A duration written as a single number where the fraction represents part of an hour: 90 minutes is 1.5 hours. |
| Hours and minutes | The clock-style form, where the second figure runs from 0 to 59 rather than as a fraction of 100. |
The inputs explained
| Field | What to enter |
|---|---|
| Convert | Choose which way to convert. |
| Hours | The whole hours, when converting to decimal. |
| Minutes | The minutes, when converting to decimal. Values above 59 still work and roll into the hours figure. |
| Decimal hours | The decimal figure, when converting back to hours and minutes. |
When to use it
Filling in a timesheet
A shift recorded as 7 hours 45 minutes goes into a decimal timesheet as 7.75, not 7.45, and the difference is 18 minutes of pay on a single shift.
Billing time to a client
Professional billing is usually in decimal hours or in fixed increments, so a session tracked on a clock needs converting before it can be invoiced.
Reading a decimal figure back
A payroll report showing 6.25 hours is 6 hours and 15 minutes, which is the form most people can check against their own record of the day.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
What do common minute values convert to in decimal hours?
Two whole hours with a range of minute values added.
| Minutes | Decimal hours | Total minutes |
|---|---|---|
| 0 min | 2.000 | 120 minutes |
| 15 min | 2.250 | 135 minutes |
| 20 min | 2.333 | 140 minutes |
| 30 min | 2.500 | 150 minutes |
| 45 min | 2.750 | 165 minutes |
Questions
Why is 2 hours 20 minutes not 2.20?
Because minutes run to 60 rather than to 100. Twenty minutes is a third of an hour, which is 0.333 in decimal, so the correct figure is about 2.33. Writing 2.20 records eight minutes less than was worked.
How should I round a recurring decimal?
Follow whatever the payroll or billing system requires, since consistency matters more than precision here. Two decimal places is the common convention, and the rounding error over a fortnight is under a minute.
What about durations over 24 hours?
The conversion is the same, since it treats the figure as a duration rather than a time of day. Forty hours and 30 minutes is 40.5 decimal hours.
Is it safer to record minutes only?
Often, yes. Total minutes is unambiguous, converts cleanly to either format, and removes any chance of a decimal being read as a clock figure or the reverse.
For the hours between two clock times, see the hours calculator. For pay based on those hours, see the salary calculator.