Minutes to Decimal

Decimal hours = minutes ÷ 60. An hour has 60 minutes, so each minute is one sixtieth of an hour, 0.0167. Twenty minutes are 20 ÷ 60 = 0.3333…, which payroll writes as 0.33. Whole hours stay as they are: 8 hours 20 minutes is 8 + 0.33 = 8.33 hours.

The reason the conversion exists is that pay is a multiplication, rate × hours, and you cannot multiply by 8:20. Every payroll system, most time clocks and the hourly fields in accounting software work in decimal hours, while people record time in hours and minutes. The chart bridges the two.

Only the minutes need converting, never the hours, and the minutes must be converted before they are added to the hours, not written after a decimal point. 8:20 is 8.33, not 8.20; the difference is 8 minutes. The same slip in the other direction turns a 0.5-hour meeting into 50 minutes.

Hundredths are minutes ÷ 60 rounded to two places and are what a pay stub shows. Tenths are the same value rounded to one place, which is how a time clock set to 6-minute rounding records it: every tenth of an hour is 6 minutes, so 12 minutes are 0.2 and 36 minutes are 0.6. Note that 15 minutes, exactly 0.25, rounds to 0.3 under the usual half-up rule, while some systems round it to 0.2; if your stub shows 0.2 for a quarter hour, that is why.

The values people look up most have their own pages, with hours-and-minutes tables, rounding and pay: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50 and 55 minutes.

Only minute values divisible by 3 give a decimal that ends: 3 minutes are 0.05, 6 are 0.1, 9 are 0.15 and so on up to 57 minutes, 0.95. Everything else repeats, which is why 20 minutes is 0.3333… and payroll has to round. The rounding error on a single value is at most half a hundredth, 18 seconds, but it should be made once, on the total, not on every line of a timesheet; ten days of 8:20 are 83.33 hours, while ten rounded values of 8.33 add to 83.30.

Multiply the decimal part by 60. 0.75 × 60 = 45 minutes; 0.33 × 60 = 19.8, which is 20 minutes once you allow for the rounding that produced the 0.33; 0.9 × 60 = 54 minutes. The hours before the point are unchanged. A pay stub showing 38.45 hours is therefore 38 hours and 0.45 × 60 = 27 minutes, not 38 hours 45 minutes; the difference of 18 minutes is the usual reason a stub and a time card seem not to match.

Spreadsheets store a time as a fraction of a day, so multiplying by 24 gives hours. The result cell must be formatted as a number, otherwise Excel shows the decimal as a time again. For durations over 24 hours, enter the time with the [h]:mm format before multiplying. The timesheet templates have these formulas built in.

On a time card, every day's minutes are converted so the week can be added and multiplied by the rate; the time card calculator shows hh:mm and decimal side by side. On a time clock that rounds, the conversion is folded into the rounding: a 6-minute clock produces tenths directly, a 15-minute clock produces quarters, 0.25, 0.50 and 0.75. In billing, lawyers and consultants record in tenths of an hour, so a 6-minute phone call is 0.1 and a 20-minute one is 0.4 after rounding up. In German-speaking payroll the same idea is called Industrieminuten, with the hour divided into 100 instead of 60.