Time Calculator

What it does

Two questions about the clock that spreadsheets make harder than they should be. Adding up durations is the timesheet question — how many hours did the week come to. Time between two moments is the shift question — when did it start, when did it end, how long was the break. Both are plain arithmetic, but the display is where tools go wrong: a total of fifty hours is fifty hours, not two, and anything that formats a duration as a time of day gets that backwards.

How to use it

1. For a total, type each duration and choose whether to add or subtract it. Blank rows are ignored.
2. For a shift, type the start and end times. If the end is earlier than the start, the page assumes it crossed midnight.
3. Read the result as hours and minutes, and as decimal hours — the form payroll usually wants.

The arithmetic runs in your browser. Nothing you type is sent anywhere and nothing is stored, so you can use these with real numbers.

Frequently asked questions

What can I type in the duration boxes?
Whatever you already write: 1:30, 01:30:00, 90m, 1h30, 1h 30m, or 1.5. A comma decimal separator works as well as a dot. Two numbers around a colon are read as hours and minutes, so 30:15 is thirty hours and fifteen minutes.

Why does my total show more than 24 hours?
Because it should. A duration is not a time of day: a week of shifts adding up to fifty hours is fifty hours. Tools that wrap the total at 24 are formatting it as a clock, which is the wrong thing entirely.

How does it handle a night shift?
If the end time is earlier than the start, the page assumes the shift crossed midnight and says so. 22:00 to 06:00 is eight hours, not minus sixteen.

What are decimal hours for?
Payroll and invoicing normally bill in decimals, not in minutes. Seven hours and thirty minutes is 7.5, and seven hours and twenty minutes is 7.33 — which is exactly the conversion people get wrong by hand.

Wikipedia — Timesheet
Wikipedia — Shift work
Wikipedia — 24-hour clock
Wikipedia — Working time