Why payroll uses decimal hours
A time clock records hours and minutes, but payroll multiplies hours by a dollar rate, and you cannot multiply 7 hours 45 minutes by $18 directly. The minutes have to become a fraction of an hour first. Forty five minutes is three quarters of an hour, so 7:45 becomes 7.75, and 7.75 × $18 = $139.50. Every payroll system, spreadsheet and pay stub works in decimal hours for this reason.
The conversion is a single division: decimal = minutes ÷ 60. Add the result to the whole hours. The chart above lists every minute from 0 to 59 so you do not have to divide at all; find the minutes on the left and read the decimal on the right.
Worked examples
| Time card shows | Minutes ÷ 60 | Decimal hours |
|---|---|---|
| 8:15 | 15 ÷ 60 = 0.25 | 8.25 |
| 7:20 | 20 ÷ 60 = 0.333… | 7.33 |
| 6:50 | 50 ÷ 60 = 0.833… | 6.83 |
| 39:40 | 40 ÷ 60 = 0.666… | 39.67 |
| 42:07 | 7 ÷ 60 = 0.116… | 42.12 |
The most common mistake: 7.30 is not 7:30
Writing 7 hours 30 minutes as 7.30 underpays by twenty minutes at a time, because 7.30 decimal hours is only 7 hours 18 minutes. The correct decimal is 7.50. The same error turns 8:45 into 8.45 instead of 8.75. Over a two week pay period with ten shifts, the gap can easily reach several hours. If a pay stub shows totals that look like clock time with a dot in place of the colon, check them against the chart.
Going the other way: decimal to hours and minutes
To turn decimal hours back into minutes, multiply the part after the point by 60. 7.75 hours is 7 hours plus 0.75 × 60 = 45 minutes. 38.4 hours is 38 hours plus 0.4 × 60 = 24 minutes. The second field in the converter does this for you as you type.
Tenths and hundredths
Some employers record time in tenths of an hour (six minute blocks) rather than exact minutes. In that system 0.1 = 6 minutes, 0.2 = 12 minutes and 0.5 = 30 minutes, and every punch is rounded to the nearest tenth. That practice is allowed under federal rules as long as it averages out fairly over time; see the time clock rounding rules guide. The chart here uses hundredths, which is what you want when no rounding is applied.
| Tenth of an hour | Minutes covered |
|---|---|
| 0.1 | 1 to 6 |
| 0.2 | 7 to 12 |
| 0.3 | 13 to 18 |
| 0.4 | 19 to 24 |
| 0.5 | 25 to 30 |
| 0.6 | 31 to 36 |
| 0.7 | 37 to 42 |
| 0.8 | 43 to 48 |
| 0.9 | 49 to 54 |
| 1.0 | 55 to 60 |
Totalling a whole week
Convert each day first or total the minutes first; the answer is the same as long as you carry minutes over 60 into the hours column. The simplest way is to skip the arithmetic and enter the punches in the time card calculator, which shows every day and the weekly total in both h:mm and decimal.