Decimal hours converter

Converting between hours:minutes and decimal hours

A decimal hour expresses the minutes as a fraction of 60 instead of a count. To go from clock form to decimal, divide the minutes by 60 and add the result to the whole hours: decimal = hours + minutes ÷ 60. To go back, keep the whole number as hours and multiply the fractional part by 60 to recover the minutes. Because 60 is not a power of ten, many minute values become repeating decimals (20 minutes is 0.333…), so a rounded figure is normally used.

Example: 7 hours 45 minutes is 7 + 45 ÷ 60 = 7 + 0.75 = 7.75 hours. In reverse, 6.4 hours is 6 hours plus 0.4 × 60 = 24 minutes, so 6 h 24 min. If a timesheet shows 3.1 hours, that is 3 h 6 min, not 3 h 10 min.

Rounding and common conversion errors

The classic slip is reading the digits after the point as minutes. 1.30 hours is 1 h 18 min, not 1 h 30 min, and writing 8.50 when you mean 8 h 50 min understates the time by 20 minutes (the correct figure is 8.83). On a monthly invoice those small gaps add up quickly, so convert each entry with the formula rather than by eye.

Decide on a rounding rule and use it consistently. Two decimal places keep the error under half a minute per entry. Some employers record time in tenths of an hour (6-minute blocks) or quarters (15-minute blocks); in the US, the Department of Labor accepts rounding to the nearest quarter hour as long as it averages out and does not consistently favour the employer. When summing a week, add the exact minutes first and convert once at the end; converting each day and rounding separately can drift by a few minutes. Spreadsheets store time as fractions of a day, so multiply a time cell by 24 to get decimal hours.