BYTETOOLS

Time Calculator

Add and subtract a chain of times and durations in hh:mm:ss with automatic carry across day boundaries, plus a decimal-hours read-out for payroll.

4:15:00
Total (h:mm:ss)
4.2500
Decimal hours
255.00
Total minutes
15300
Total seconds

Calculation

1:45:00 + 2:30:00 = 4:15:00 (4.2500 hours)

Days and hours: 4h 15m 0s

What is the Time Calculator?

The ByteTools Time Calculator does arithmetic on durations. Enter a starting value in hh:mm:ss, then add or subtract as many further times as you like — the running total carries seconds into minutes and minutes into hours automatically, so 45:30 plus 20:45 correctly becomes 1:06:15 rather than an impossible 65 minutes.

  • Chain any number of add and subtract steps
  • Correct carry across second, minute, hour and day boundaries
  • Decimal-hours, total-minutes and total-seconds read-outs
  • Handles negative totals with a clear sign
  • One-click copy of the full calculation
  • Fully offline — no data leaves your browser

How to use the Time Calculator

  1. 1

    Enter your first time or duration as hours, minutes and seconds.

  2. 2

    Press Add row to append another value and choose plus or minus for it.

  3. 3

    Watch the running total update as you type.

  4. 4

    Read the answer in hh:mm:ss, decimal hours, total minutes and total seconds.

  5. 5

    Copy the result or clear the list to start again.

About the Time Calculator

The ByteTools Time Calculator does arithmetic on durations. Enter a starting value in hh:mm:ss, then add or subtract as many further times as you like — the running total carries seconds into minutes and minutes into hours automatically, so 45:30 plus 20:45 correctly becomes 1:06:15 rather than an impossible 65 minutes.

It is built for timesheets, video and audio edit lists, race splits, cooking schedules and billing. Alongside the hh:mm:ss total you get the same figure in decimal hours, total minutes and total seconds, which is what most payroll and invoicing systems actually want you to type in.

Negative results are supported and clearly signed, so subtracting a larger duration from a smaller one gives a sensible answer instead of a wrapped-around one. All the arithmetic happens locally in your browser — nothing is uploaded.

Frequently asked questions

How do you add hours and minutes together?

Add the seconds, minutes and hours as separate columns, then carry every 60 seconds into a minute and every 60 minutes into an hour. This calculator does that for you, so 1:45 plus 2:30 comes out as 4:15 instead of 3:75.

What is 7 hours 45 minutes in decimal hours?

It is 7.75 hours, because 45 minutes is 45 divided by 60, which is 0.75. The decimal-hours read-out shows this automatically, which is the format most payroll and invoicing systems expect.

Can this calculator handle times over 24 hours?

Yes. Durations are not clock times here, so a total of 39:20:00 stays as 39 hours 20 minutes rather than wrapping around to 15:20. A days-and-hours breakdown is also shown once the total passes 24 hours.

What happens if I subtract a bigger time from a smaller one?

You get a negative duration, shown with a leading minus sign. That is usually what you want when tracking a deficit against a target — for example being 0:35:00 short of a 40-hour week.

How is this different from a duration calculator?

A duration calculator finds the gap between two clock times, such as 9:00 to 17:30. This tool adds and subtracts durations that you already have, which is what you need when combining several timesheet entries or edit-list segments.

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