FreeToolStation

Time Duration Calculator

Add, subtract and measure durations.

Date & Time Calculators Free, no sign-up Runs in your browser

Earlier than the start means the next day.

Used when totalling a list. Hours and minutes, like 1:30.

—
Result
—
As decimal hours
—
Total minutes
—
As days and hours

About the Time Duration Calculator

Time Duration Calculator handles the arithmetic that clock time makes awkward: the gap between two times, a duration added to or taken from a time, and the total of a list of durations.

Time is base sixty, which is why adding it by hand goes wrong. 2:45 plus 1:30 is 4:15, not 3:75, and the carry has to happen at sixty rather than a hundred. Subtracting across midnight is worse: the gap from 22:30 to 06:15 is 7 hours 45 minutes, and getting there by hand means borrowing twenty-four. The calculator does both correctly and shows the working.

Crossing midnight is handled explicitly rather than guessed at. If the end time is earlier than the start, it is assumed to be the next day, which is what somebody calculating a night shift wants. Where that assumption would be wrong, there is a date field to make it unambiguous.

Durations can be totalled as a list, which is the common case for timesheets, study logs and billing. The total is given in hours and minutes and as a decimal, since invoicing and payroll almost always want the decimal form and converting 7 hours 20 minutes to 7.33 is another step that gets done wrong by hand.

Everything is worked out inside your browser. Nothing you enter is uploaded, logged or stored, which matters for the financial calculators in particular: the figures you put into them are nobody else's business.

Looking for something this does not cover? FreeToolsZone.org is more free browser-based tools, organised by job, and it is worth a look if time duration calculator is only part of what you are working on.

How to use the Time Duration Calculator

  1. Choose the modeDifference between two times, add or subtract, or total a list.
  2. Enter the timesIn 24-hour or 12-hour format, with dates where it matters.
  3. Read the resultHours and minutes, with the decimal equivalent alongside.
  4. Copy or downloadThe total, or the whole list with its running sum.

Features

  • Difference between two times, including across midnight
  • Add or subtract a duration from a time
  • Total a whole list of durations
  • Decimal hours given for payroll and invoicing
  • 12-hour and 24-hour input, with seconds if you need them
  • Dates supported when the gap spans more than a day
  • Runs in your browser

Who uses this tool

The time duration calculator is used by writers, developers, students, marketers and anyone else who needs the job done once without installing software. Common cases include:

  • Working out the length of a shift that crosses midnight
  • Totalling billable hours for an invoice
  • Adding up study or practice time for a week
  • Finding when something will finish from a start time and a duration
  • Converting worked hours into the decimal form payroll wants

Frequently asked questions

Does it handle times crossing midnight?

Yes. If the end time is before the start, the next day is assumed, which is what a night shift needs. Add dates to make it explicit.

Why do I need decimal hours?

Payroll and invoicing systems almost always want them. 7 hours 20 minutes is 7.33 hours, and the conversion is an easy one to get wrong by hand.

Can I total a long list?

Yes. Paste one duration per line and the total appears with a running sum down the list.

Does it account for time zones?

No, and deliberately: it works in plain clock time. For times in different zones, the Time Zone Converter handles the offset first.

If the time duration calculator is not quite what you need, these other free tools solve closely related problems, and there are 13 more in date & time calculators.

Work Hours Calculator

Daily and weekly hours with breaks deducted, plus overtime and gross pay.

Date & Time Calculators Use tool

Date Calculator

Add days, weeks or months to a date, or count the gap between two dates.

Date & Time Calculators Use tool

Age Calculator

Enter a date of birth to get an exact age plus total months, weeks and days.

Date & Time Calculators Use tool

Time Zone Converter

Convert times across time zones, with daylight saving handled correctly.

Utility Tools Use tool

Checked and rebuilt on 2026-10-14. The method this calculator uses is described in the section above, and corrections go through the contact page.