Convert hours and minutes into decimal hours for payroll and invoicing — and convert them back again when you need a readable duration.
Payroll and invoicing systems want decimal hours; people record time in hours and minutes. The conversion is minutes divided by sixty, and the reason it goes wrong so often is that the two notations look almost identical: 7h 45m becomes 7.75, but it is very easy to type 7.45 and never notice.
That error is 18 minutes per entry in the wrong direction, and it is systematic rather than random, so it never averages out across a month.
The classic case: 45 minutes is three quarters of an hour, so .75 and not .45.
Converting back — 0.7 hours is 42 minutes, not 70.
Add durations first, convert once at the end. Converting each entry compounds rounding.
A whole shift straight into the decimal figure payroll expects.
Divide the minutes by 60 and add them to the hours. 7 hours 45 minutes is 7 + 45/60 = 7.75 hours. The common mistake is writing 7.45, which is 7 hours 27 minutes — an 18-minute error.
0.75 hours. Likewise 15 minutes is 0.25, 30 minutes is 0.5, and 20 minutes is 0.333 recurring. Any minute value works the same way: divide by 60.
Multiply the decimal part by 60. 7.75 hours is 7 hours plus 0.75 x 60 = 45 minutes. So 0.7 hours is 42 minutes, and 0.25 hours is 15 minutes.
Convert once at the end wherever your agreement allows it. Rounding every daily entry to two decimal places and then summing introduces error that compounds across a month; adding the durations first and converting the total does not.