Time Duration Calculator
Add up hours and minutes without getting 21:90 — and get the decimal total payroll asks for.
Runs entirely in your browser
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How to use
- Paste one duration per line, in whichever notation your notes use.
- Add a comment after # to label a line — Monday, project name, anything.
- Read the total in hours and minutes, or the decimal version for a payroll form.
- Put a minus in front of a line to subtract a correction.
Features
- Mixes 7:45, 7h45, 7.75, 90m and bare numbers in one list.
- Carries minutes into hours properly — the sum is never 21:90.
- Gives the decimal total, which is what timesheet software takes.
- Negative entries for corrections, comments for labels.
- Runs entirely in your browser.
Frequently asked questions
- Why not just add the times in a spreadsheet?
- Because a spreadsheet reads 7:45 as a time of day and 7.45 as a decimal, and mixing the two is where the errors come from. 7:45 + 8:30 is 16 hours 15 minutes; treating them as decimals gives 15.75, which is 24 minutes short. This works in whole minutes and only formats at the end.
- What does a bare number mean?
- Hours. Writing `8` on a timesheet means eight hours everywhere it is written, so that is how it is read. When you mean minutes, mark them: `90m`.
- Why is the decimal total useful?
- Because payroll systems and invoices are usually filled in with decimal hours: 7 hours 45 minutes is 7.75, not 7.45. Converting by hand is where an hour goes missing at the end of a month.
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