NHS Shift Hours Calculator Guide

Use the NHS shift hours calculator

To calculate a shift, you need three figures:

• shift start time
• shift finish time
• total unpaid break time

Once you have those three figures, you can work out:

• total shift span
• paid shift length
• hours and minutes
• decimal hours

This is useful for checking rota hours, timesheets and the paid shift length you may need for annual leave calculations. Once you have the paid shift length, the Hundred Hour Time Converter turns it into decimal hours.

How to calculate an NHS shift manually

The basic formula is:

Finish time − start time − unpaid breaks = paid shift length

For example:

• Start: 07:30
• Finish: 15:30
• Elapsed time: 8 hours
• Unpaid break: 30 minutes

Paid shift: 7h 30m, or 7.50 decimal hours

12-hour NHS shift example

Suppose you work 07:00–19:00.

The total time from start to finish is 12 hours.

If you have a 30-minute unpaid break, then:

12h − 30m = 11h 30m

So the paid shift length is 11h 30m. In decimal hours: 11.50 hours.

This is an important distinction. A 12-hour shift span does not always mean 12 paid hours.

NHS night shift across midnight

Night shifts can look more confusing because the finish time is on the following day.

For example:

• Start: 19:30
• Finish: 07:30 next day

The total shift span is 12 hours.

Now subtract a 30-minute unpaid break:

12h − 30m = 11h 30m

Paid shift: 11h 30m, or 11.50 decimal hours

The important point is to treat the finish time as occurring on the following day.

Paid vs unpaid breaks

Breaks only reduce paid shift hours if they are unpaid.

Unpaid break

Subtract it from the shift duration.

12-hour shift − 30-minute unpaid break = 11h 30m paid

Paid break

Do not subtract it from paid hours.

12-hour shift with a paid 30-minute break = 12 paid hours

Local arrangements can differ, so check whether your break is paid or unpaid before using it in the calculation.

What if you have more than one unpaid break?

Add all unpaid breaks together first.

For example, a 30-minute unpaid break plus a 15-minute unpaid break:

30m + 15m = 45m total unpaid break

If the shift span is 12 hours, then:

12h − 45m = 11h 15m

So the paid shift is 11h 15m. In decimal hours: 11.25 hours.

11h 30m is not 11.30 decimal hours

This is one of the most common decimal-time mistakes.

If you work 11h 30m, the decimal result is 11.50 hours, not 11.30 hours.

That is because:

30 minutes ÷ 60 = 0.50 hours

So 11h 30m = 11.50 hours.

By comparison, 11.30 decimal hours means 11 hours + 0.30 of an hour:

0.30 × 60 = 18 minutes

So 11.30 decimal hours = 11h 18m.

In other words: 11:30 ≠ 11.30

Quick NHS shift-hours examples

These examples assume all listed breaks are unpaid.

Which figure should you use?

Different tasks need different time figures.

For the rota span

Use start time to finish time. For example: 07:00–19:00 = 12 hours.

For paid working hours

Use shift span − unpaid breaks. For example: 12h − 30m = 11h 30m.

For a decimal timesheet

Use the paid shift length converted into decimal hours. For example: 11h 30m = 11.50.

For annual leave conversion

Use the paid shift length. For example, if your paid shift is 11h 30m, use 11.5 hours when converting leave hours into shifts.

Why paid shift hours matter for annual leave

If your annual leave is shown in hours, the paid length of your shift can affect how many leave hours a particular shift represents.

For example:

• Shift span: 12h
• Unpaid break: 30m
• Paid shift: 11h 30m

For leave conversion, the useful figure may therefore be 11.5 hours rather than 12 hours.

Once you know your paid shift length, see the NHS Holiday Hours to Shifts Calculator Guide.

Why decimal hours matter for timesheets

Some payroll and timesheet systems use decimal hours rather than hours and minutes.

For example, 7h 30m is 7.50 decimal hours, not 7.30.

Likewise:

• 11h 15m = 11.25 hours
• 11h 45m = 11.75 hours

If you enter clock-style minutes directly into a decimal system, the result can be wrong.

For more detail, see How to Convert a Timesheet to Decimal Hours.

Shift span, paid shift and contracted hours are different

These figures can easily be confused.

For example:

• Contracted weekly hours: 37.5h
• Shift span: 12h
• Paid shift length: 11h 30m

Your contracted hours describe your overall working commitment.

Your shift span describes one individual start-to-finish period.

Your paid shift length is the time left after unpaid breaks are removed.

For a fuller explanation, see NHS Contracted Hours and Shift Lengths Explained.

Common mistakes when calculating NHS shift hours

Forgetting to subtract unpaid breaks

If a break is unpaid, it reduces the paid shift length.

Subtracting a paid break

Paid breaks remain part of paid working time.

Entering 11.30 when you mean 11h 30m

11h 30m equals 11.50 decimal hours.

Getting an overnight shift wrong

If a shift finishes after midnight, the finish time is on the following day.

Confusing shift span with paid hours

A 12-hour start-to-finish span may only contain 11.5 paid hours.

Using contracted weekly hours to calculate one shift

Your contract might say 37.5 hours per week, but that does not tell you the length of an individual shift.

Forgetting to combine multiple unpaid breaks

Add all unpaid breaks together before subtracting them.