Hours and minutes calculator
Add and subtract time segments without tripping over base 60. Perfect for working out hours worked, clock-ins, shifts and overtime.
Use the sign on each row to add (+) or subtract (−) segments.
Why adding up hours by hand goes wrong so often
The root of the problem is that minutes run in base 60 while we're used to thinking in base 10. Add 1 h 45 min and 1 h 30 min "as normal numbers" and you get 2.75, and assume it's almost three hours, when it's really 3 h 15 min. The trick that never fails is to convert everything to minutes before you start: 105 minutes plus 90 is 195, which divided by 60 gives 3 hours with 15 minutes left over. That's exactly what this tool does with each block, adding or subtracting depending on the sign.
Decimal hours: what your payroll needs
One detail trips a lot of people up when working out pay. If your rate is hourly and you work 7 h 30 min, you don't multiply by 7.30 but by 7.5, because those 30 minutes are half an hour, that is, 0.5. That's why the tool also gives the result in decimal hours: it's the format you need to multiply by a rate or drop into a spreadsheet. For reference: 15 min is 0.25 h; 20 min, 0.33 h; 40 min, 0.67 h; and 45 min, 0.75 h.
Where it helps day to day
The headline use is tracking working time: adding up a week's hours from clock-in and clock-out times, totting up a month's overtime or splitting time across projects. The option to subtract blocks is handy for taking out a lunch break or a couple of hours off in the morning.
Not just for work
It works for any sum that involves a clock: how much you've slept this week, the total length of a playlist, study hours before an exam or the time you've put into a hobby. If you subtract more than you add and the total comes out negative, it's shown with its sign, so you can also see how much you're short of, or over, a target.