Hours Calculator
Add and subtract hours and minutes. Totals in h:mm, decimal hours, and minutes.
Minutes above 59 are fine: enter 90 minutes and it rolls into 1h 30m. Subtracting more than you have added gives a negative total rather than an error. Lines save in your browser.
Adding time is the one bit of arithmetic that a calculator app makes harder. Hours run in sixties, not tens, so 2:45 plus 3:30 is not 5.75 on a keypad, and after four or five entries you have lost track of which carries you already did.
This page counts in base 60 for you. One line per block of time, plus or minus, and the total sits underneath in every format anyone is likely to ask for: 6h 15m for a human, 6:15:00 for a spreadsheet, 6.25 for payroll.
Nothing is uploaded and there is nothing to sign up for. Your lines stay in the browser, so you can close the tab mid-timesheet and pick it up later.
How the total is worked out
Every line is converted to seconds: hours times 3,600, plus minutes times 60, plus any seconds. Lines marked minus are subtracted, and the total is converted back into hours and minutes, clock format and decimal hours.
Working in seconds is what makes the carries come out right. Sixty minutes becomes an hour automatically, however the lines were typed.
A worked example
A week of 7h 45m, 8h 20m, 6h 50m and 9h 05m adds up to exactly 32 hours. Take off a 1h 30m appointment and the total is 30h 30m, or 30.5 decimal hours for payroll.
Type the same week into an ordinary calculator as 7.45 + 8.20 + 6.50 + 9.05 and you get 31.2, which is 48 minutes short, because the calculator treats the minutes as hundredths of an hour.
Mistakes to avoid
Writing minutes as decimals. 7h 45m is 7.75 decimal hours, not 7.45, and the gap grows with every line you add.
Rounding each day before adding. Rounding every line to the nearest quarter hour can add or lose several minutes a week. Add the exact times first and round the total, if your employer rounds at all.
Mixing clock times with durations. This calculator adds lengths of time. To find how long it was between a start and an end time, use the time duration calculator.
You are adding up hours you already worked.
Every line here is a session you had to remember. PomoTodo logs them as they happen, tags each one to a task or client, and hands you the total at the end of the week already in decimal hours.
Free plan tracks unlimited focus time across unlimited tasks. No card required.
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Questions
How do I add hours and minutes together?
Type each block of time on its own line, with hours in the first box and minutes in the second, and add a line for every entry you need. The total updates as you type and is shown in h:mm, in clock format, and in decimal hours.
Can I subtract time as well as add it?
Yes. Tap the plus button on any line to flip it to minus. That line is then taken off the running total, which is the quickest way to remove lunch breaks or non-billable time from a day.
What if I enter more than 60 minutes?
It still works. Ninety minutes is read as 1 hour 30 minutes, so you can type numbers straight off a timesheet without converting them first.
What are decimal hours and why does the calculator show them?
Decimal hours express minutes as a fraction of an hour, so 7 hours 30 minutes becomes 7.5. Payroll systems and invoice templates almost always want this format rather than h:mm, so the total is given both ways.