Zerdly

Time Duration Calculator

Work out net hours between two times or dates, less paid or unpaid breaks, in h:mm and decimal hours — with next-day and daylight-saving handling.

100% FreeRuns in your browserBasic
How to use this calculator

Shifts

Gross, breaks and net time — in h:mm and decimal hours.

If the end is earlier than the start, tick “Ends next day” — it is never assumed.

Shift 1
Start
End
Payroll rounding (off)

Applied per shift to the net time. The raw time is always shown beside it. Whether rounding is allowed is a matter for your employment terms.

Enter a start and end and press Calculate.

Shift and break timeline
Not to scale between shifts
Shift and break timelineEach shift as a horizontal bar from start to end, with unpaid breaks hatched and paid breaks outlined.Start → EndUnpaid breakPaid break
Each shift is drawn as a bar from start to end with its breaks marked inside it.

How to use this calculator

  1. Choose clock times, dated wall-clock times, or dated times in a time zone.
  2. Enter the start and end. For clock times that cross midnight, tick “Ends next day” — it is never assumed.
  3. Add breaks as a length or as from–to times and mark any that are paid. Add more shifts to total them, then press Calculate.

How it works

Net = (end − start) − unpaid breaks; decimal hours = seconds ÷ 3600. Paid breaks are listed but not deducted. Timed breaks must sit inside the shift and may not overlap, and breaks may not add up to more than the shift.

In time-zone mode the start and end are converted with your browser's built-in time-zone rules, so elapsed time includes a daylight-saving change; the wall-clock difference is shown beside it. A time that happens twice when clocks go back asks which one you mean, and a time skipped when clocks go forward is an error.

No rounding is applied unless you choose an increment, and then the raw and rounded values are both shown. Nothing here checks award, payroll or break-law compliance.

Worked example

09:00 to 17:30 with a 30-minute unpaid break. 8 h 30 m gross − 30 m = 8 h 00 m net = 28,800 seconds = 8.0 decimal hours. An overnight 23:00 to 01:00 with “Ends next day” is 2 h.

Tips

  • Runs entirely in your browser. Your inputs are not saved or transmitted.

Frequently asked questions

Next day or same day?

With clock times only, an end earlier than the start is an error until you tick “Ends next day”, so 23:00 to 01:00 becomes 2 hours rather than a guess. With dates, the dates decide.

Decimal hours or h:mm?

Both are shown. 8 h 15 m is 8.25 decimal hours (15 ÷ 60); payroll systems usually want decimals, rosters usually show h:mm.

What happens at DST changes?

Choose time-zone mode. When clocks go forward an hour, a 01:00–04:00 shift on the wall clock is only 2 hours of elapsed time (Sydney, 4 October 2026); Perth, with no daylight saving, stays 3 hours. Wall-clock mode ignores the change and says so.

Privacy?

Runs entirely in your browser. Your inputs are not saved or transmitted.

Related tools

Explore more in Time, Date, Roster & FIFO.

Cite this tool

Zerdly. (2026). Time Duration Calculator. Retrieved from https://www.zerdly.com/tools/time-duration-calculator/

Tip: Enter any known values to calculate the remaining results.

Designed to run locally in your browser. Tool inputs are not intentionally stored by Zerdly unless stated otherwise.