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Date & Time

Time Duration Calculator

Add, subtract and convert hours, minutes and seconds.

Enter your values

Enter the first duration in HH:MM:SS.

Enter the second duration in HH:MM:SS.

Choose one of: Add, Subtract.

Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.

Results
Result
4:05:45
Decimal hours
4.0958
Total minutes
245.75
Total seconds
14,745

Quick answer

Convert both durations to seconds, add or subtract, then convert back to hours, minutes and seconds.

At a glance

What it doesAdd, subtract and convert hours, minutes and seconds.
CategoryDate & Time
Inputs neededFirst duration, Second duration, Operation
Main outputResult
CostFree — no sign-up, no download

How to use the Time Duration Calculator

  1. 1Enter the first duration as HH:MM:SS.
  2. 2Enter the second duration.
  3. 3Choose add or subtract.

Inputs explained

First duration(HH:MM:SS)
Enter the first duration in HH:MM:SS.
Second duration(HH:MM:SS)
Enter the second duration in HH:MM:SS.
Operation
Choose one of: Add, Subtract.

Worked example

Using the values the calculator loads with:

Inputs

  • First duration02:45:30 HH:MM:SS
  • Second duration01:20:15 HH:MM:SS
  • OperationAdd

Results

  • Result4:05:45
  • Decimal hours4.0958
  • Total minutes245.75
  • Total seconds14,745

Frequently asked questions

Why is 1:30 not 1.30 hours?

Minutes are sixtieths, so 1:30 is 1.5 decimal hours. Payroll and billing always use the decimal form.

Can I enter durations over 24 hours?

Yes — the hours field is not capped, so 36:00:00 is valid.

What do I need to enter into the Time Duration Calculator?

Just 3 values: first duration, second duration, operation. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.

How does the Time Duration Calculator work out the answer?

Convert both durations to seconds, add or subtract, then convert back to hours, minutes and seconds. The working is shown step by step so you can verify the result by hand.

Is the Time Duration Calculator free, and do I need an account?

It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.

Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.