Quick answer: To convert minutes to decimal hours, divide the minutes by 60. To convert hours and minutes, keep the whole hours and add the minute fraction.
Try it: Open the free BuzBolt Time Calculator. No signup is required.
The formula
Decimal hours = whole hours + (minutes ÷ 60).
For 8 hours 30 minutes, calculate 8 + 30/60 = 8.50. For 7 hours 20 minutes, calculate 7 + 20/60 = 7.3333…. You may display the latter as 7.33, but maintain the full precision in calculations when practical.
Minutes to decimal-hours reference chart
| Minutes | Decimal hours (rounded to 4 places) | Minutes | Decimal hours (rounded to 4 places) |
|---|---|---|---|
| 5 | 0.0833 | 35 | 0.5833 |
| 10 | 0.1667 | 40 | 0.6667 |
| 15 | 0.2500 | 45 | 0.7500 |
| 20 | 0.3333 | 50 | 0.8333 |
| 25 | 0.4167 | 55 | 0.9167 |
| 30 | 0.5000 | 60 | 1.0000 |
A conversion chart is useful for checking a calculation, but a formula is more accurate for values such as 1, 7 or 13 minutes.
Example: a time record with a break
A shift from 09:10 to 17:40 lasts 8h 30m. If 40 minutes are excluded as an unpaid break, the remaining time is 7h 50m. In decimals: 7 + 50/60 = 7.8333… hours. The time 7:50 and number 7.83 are different representations of the same duration.
Converting back to hours and minutes
Take 6.75 hours. The whole number is 6 hours. The fractional 0.75 × 60 gives 45 minutes, so the result is 6h 45m. To avoid precision issues, do not interpret 6.75 as 6h 75m.
Excel and Google Sheets
If A2 is a start time and B2 is an end time, =MOD(B2-A2,1)*24 calculates decimal elapsed hours for less-than-24-hour intervals, including overnight shifts. With a break in minutes in C2, use =MOD(B2-A2,1)*24-C2/60. Use standard time-formatted inputs and date-time values when intervals can span multiple days.
Accuracy and rounding
Some minute values produce repeating decimals. For example, 10 minutes equals 0.16666… hours. Two decimal places show 0.17, four show 0.1667. These are display formats, not different underlying durations. Do not assume a particular rounding method is appropriate for every workplace or invoice: this article explains numerical conversion only.
Common mistakes
- Using the minute count after the decimal point, such as writing 6.45 for 6h 45m.
- Dividing minutes by 100 instead of 60.
- Mixing time-of-day cells with decimal-number cells in a spreadsheet.
- Adding already-rounded decimal-hour values over a long period.
Why a decimal chart is useful—but not a substitute for the formula
For familiar quarter hours, people often remember 0.25, 0.50 and 0.75. Less familiar values are easier to check on a chart, such as 35 minutes = 0.5833… hours. But the underlying formula always remains minutes divided by 60. Using the formula avoids introducing a different rounding convention for each row.
An invoice might show 7.5 billable hours, while a time record shows 7h 30m. Both can be perfectly clear if the unit is stated. Trouble begins when 7.30 is written without context; in a decimal column it means 7.3 hours, or 7h 18m, not 7h 30m.
Choosing sensible precision
Decide whether your output is a time record, a calculation input or a formatted display. Preserve exact minutes as long as possible. If an interface rounds to two decimals, readers should understand that the result is displayed approximately when necessary. Different organisations can use different rounding procedures; this guide does not set one.
More reading
BuzBolt provides general educational tools and explanations. Check your inputs and confirm any legal, tax, accounting or workplace-specific requirements independently where relevant.