Time duration calculator

Three ways to write the same answer

From 09:00 to 17:30 is 8 hours and 30 minutes. It is also 8.5 hours, and 510 minutes. All three are shown because different jobs want different ones: a timesheet is filled in hours and minutes, payroll and invoicing work in decimal hours because they multiply cleanly by a rate, and minutes are what you want when adding several spans together.

The conversion between the first two is where mistakes happen. 8 hours 30 minutes is 8.5, but 8 hours 15 minutes is 8.25, not 8.15, and 8 hours 20 minutes is 8.33. Minutes are sixtieths, not hundredths, and writing them straight after a decimal point quietly overpays or underpays.

Shifts that run past midnight

Enter 22:00 to 06:00 and the answer is eight hours, an end time earlier than the start is read as the following day, because that is what a night shift is. The result says when it has done this, so you can check the reading is the one you meant.

One case is deliberately not guessed at: entering the same time twice gives zero rather than twenty-four hours. A duration between a moment and itself is nothing, and assuming a whole day would be inventing an instruction. If that is what you want, measure across dates instead and name the two days.

Clock time, not elapsed time

This measures what the two clock readings differ by. From 01:00 to 05:00 is four hours here, every time. On the two nights a year when the clocks move, the time that actually passes is three hours or five.

That is a deliberate limit rather than an oversight. Getting it right would mean knowing your timezone and its daylight-saving rules, and a payroll figure quietly an hour short twice a year is far harder to spot than one that never claimed to handle the change. Clock time is also what a timesheet actually records, which is what most people are filling in.

Breaks

The break field takes a number of minutes off the total, and does nothing else. There are no rules here about when a break is owed, how long it must be, or whether it is paid, because all of that depends on the country, the contract and the length of the shift. Enter what applies to you. If the break is longer than the span, the result stops at zero and says so rather than reporting negative hours.