Time Calculator

Add or subtract two lengths of time.

ADD & SUBTRACT - HH:MM:SS - RUNS ON YOUR DEVICE

Your numbers stay on your device

In practice

What you can count on

Specification

How to

1
Enter the First Duration
Type a length of time as h:mm or h:mm:ss, such as 02:45:00. Hours are not capped at 24.
2
Add or Subtract
Choose add or subtract, then type the second duration the same way.
3
Read the Result
The answer appears as h:mm:ss, and again in minutes, in hours and in seconds.

Questions

Neither. It adds and subtracts lengths of time. For a span between two dates and times, use the Duration Calculator instead.

h:mm or h:mm:ss — 2:45 or 02:45:00. Hours are not capped at 24, so 30:00:00 is a perfectly good length of time.

You get a negative length, shown with a minus sign in front. Nothing wraps around a clock, because there is no clock here.

Background

Enter two durations as h:mm or h:mm:ss and choose add or subtract. The answer is shown as h:mm:ss and again in minutes, in hours and in seconds.

A duration is a length, not a point on a clock: 30:00:00 means thirty hours, which no clock face can show.
Reading the same answer in minutes, hours and seconds saves converting it by hand for a timesheet or an invoice.

Specification of the Time Calculator tool
What you enter	Two durations written h:mm:ss, and whether to add or subtract the second one.
Durations only	The panel works on lengths of time. There is no clock time and no date here.
What comes back	The result, and the same answer in minutes, in hours and in seconds.
How many at once	One pair of durations at a time.
Where it runs	Everything happens in your browser tab. What you type never leaves the device.
Price	Free
Account required	No

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