Zerdly

Shift Length Calculator

The Shift Length Calculator works out the paid hours in a single shift, including shifts that run past midnight and an unpaid meal break. Punch in your start and end times on a 24-hour clock and the minutes of unpaid break, and it returns the gross shift length and the paid hours in both decimal and h:mm form — handy for checking a roster line or a timesheet before it goes to payroll.

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How to use this calculator

Enter Values

Range 0–23

Range 0–59

Range 0–23

Range 0–59

Minimum 0

Enter your values and press Calculate to see results.

How to use this calculator

  1. Enter the start hour (and start minute if not on the hour) using the 24-hour clock — 6 for 6am, 18 for 6pm.
  2. Enter the end hour and minute the same way; if the end is at or before the start, the shift is treated as running overnight.
  3. Enter the unpaid break in minutes (0 if none), then read the gross shift length and the paid hours.

How it works

Start and end are converted to decimal hours (hour + minute / 60). If the end time is at or before the start, 24 hours are added so an overnight shift measures correctly. Gross shift length is end minus start; paid hours subtract the unpaid break (minutes / 60). A 6:00 to 18:00 shift with a 30-minute unpaid break is 12.00 gross hours and 11.50 paid hours (11:30). An 18:00 to 06:00 night shift crosses midnight, so it is 12.00 gross hours, and with a 60-minute break it pays 11.00 hours.

Worked example

Worked example. A day shift from 06:00 to 18:00 with a 30-minute unpaid break runs 12.00 gross hours and pays 11.50 hours (11:30). Swap it to a night shift from 18:00 to 06:00 with a 60-minute break and it is still 12.00 gross hours but pays 11.00 hours.

Common mistakes

  • Deducting a break that is actually paid — some awards and EBAs pay the meal break, in which case the paid hours equal the gross hours.
  • Entering times on a 12-hour clock: use 24-hour values (13 for 1pm, 18 for 6pm) so afternoon and night shifts are read correctly.
  • Expecting penalty rates in the result — this tool counts hours only and does not apply night, weekend or public-holiday loadings.

Frequently asked questions

How does it handle a night shift that finishes the next morning?

If the end time is at or before the start time, the calculator adds 24 hours so the shift is measured across midnight. An 18:00 start and 06:00 finish correctly reads as 12 gross hours.

Should I include my break as paid or unpaid?

Enter only the unpaid portion. Check your award or EBA — where a break is paid it is not deducted, so you would enter 0 minutes of unpaid break for that shift.

Related tools

Explore more in Time, Date, Roster & FIFO.

Cite this tool

Zerdly. (2026). Shift Length Calculator. Retrieved from https://www.zerdly.com/tools/shift-length-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.