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WGX

Time Calculator

Add or subtract hours, minutes and seconds.

Line 1
Line 2

Total timeExample

1:45:00

1.75 decimal hours

0 seconds

What this does

Adds and subtracts lengths of time. Put a duration on each line, choose + or −, and the total updates as you type — in hours, minutes and seconds, in decimal hours, and in words.

It works on durations, not clock times. To find how long you worked between two times of day, use the Work Hours Calculator.

How to use it

  1. Enter hours, minutes or seconds on the first line. Blank fields count as zero.
  2. Enter a second duration on the next line.
  3. Switch a line to − to take it away instead of adding it.
  4. Add more lines if you have more durations.

A worked example

Three blocks of billable work in a day, minus a call that was not billable:

  • + 2 hours 30 minutes
  • + 1 hour 45 minutes
  • + 25 minutes
  • − 15 minutes

The total is 4:25:00, or 4.42 decimal hours. Done by hand, the minutes column alone comes to 85 — 30 + 45 + 25 − 15 — which has to be carried into 1 hour 25 minutes, and that is where the carrying goes wrong.

Why time does not add up in tens

Everyday arithmetic is base 10; time is base 60. Adding 45 minutes to 30 minutes gives 75 minutes, which has to be carried into an hour and 15 minutes. A pocket calculator will not do that. Type 1:45 plus 1:30 into one as 1.45 + 1.30 and it answers 2.75 — which is neither 2 hours 75 minutes nor 2 hours 45 minutes; the real total is 3 hours 15 minutes. Convert to decimal hours first and it works: 1.75 + 1.5 = 3.25.

The conversion in both directions:

decimal hours = hours + (minutes ÷ 60) + (seconds ÷ 3600)

minutes = decimal fraction × 60

So 0.25 hours is 15 minutes, 0.4 hours is 24 minutes and 0.75 hours is 45 minutes. This page shows the total both ways at once, so there is nothing to convert and nothing to misread.

Common uses

  • Totalling blocks of billable time across a day.
  • Adding up practice, study or training sessions for the week.
  • Checking that segments of audio or video fit a slot.
  • Working out how far over or under a budgeted time you are.
  • Combining cooking or process stages into an end-to-end time.

What this does not do

It does not multiply or divide a duration, add a duration to a date or a clock time, or know anything about time zones or daylight saving. Each of those is a different question, and answering it here would make this page slower to use for the question it does answer.

Questions

How do I add 2:30 and 1:45?

Add the minutes first: 30 plus 45 is 75, which is 1 hour 15 minutes. Carry that hour, so 2 plus 1 plus 1 is 4, leaving 4:15:00. Entering both lines above does the carrying for you.

Why is 1.5 hours not 1:50?

An hour has 60 minutes, not 100. Half an hour is 30 minutes, so 1.5 hours is 1:30:00. The decimal figure and the clock figure describe the same length of time in different bases, which is why this page shows both.

Can I enter more than 60 minutes?

Yes. Entering 90 minutes is the same as entering 1 hour 30 minutes, and the total rolls it up for you. The same goes for seconds.

Can the total be negative?

Yes, and it says so plainly: -1:30:00, or "minus 1 hour 30 minutes". Subtracting more than you added is an answer, not a mistake, and it is often the point — for instance when working out how far under a budgeted time you are.

Does it add a duration to a clock time?

No. This page does arithmetic on lengths of time. To find how long you worked between two clock times, use the Work Hours Calculator, which is linked from this page.

Is anything I enter sent anywhere?

No. The arithmetic runs in your browser. Nothing you type is transmitted, stored or logged.