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How to count night hours in rotating shifts

Turna team · 20 September 2026 · 5 min read

Knowing how many night hours you have worked this month ought to be easy and almost never is, especially when the shift starts one day and ends the next. Here is the calculation, step by step, and where the line sits between what can be stated and what depends on your collective agreement.

What counts as a night hour

In Spain, the Workers' Statute treats work done between ten at night and six in the morning as night work. It is not something each company makes up: it is the band set by law and the one collective agreements use as their reference. If you work elsewhere, check the band your own law or agreement sets — the method below does not change, only the two times.

That means what counts is not "doing the night shift", but how many hours of your shift fall inside that band. A shift from 20:00 to 04:00 is not eight night hours: it is six, because the first two are outside it.

The calculation when the shift crosses midnight

This is where most home-made sums go wrong. If you subtract the start time from the end time and the shift crosses twelve, you get a negative number; and if you patch it by eye, you almost always end up with an hour too many or too few.

The right way is to think of the shift as one continuous interval and look at how much it overlaps the 22:00-06:00 band. Three examples:

• 22:00 to 06:00 → 8 hours worked, 8 at night. It matches the band exactly.
• 20:00 to 04:00 → 8 hours worked, 6 at night. The first two fall outside.
• 05:00 to 13:00 → 8 hours worked, 1 at night. Only the first one is inside the band.

This is not a rare case: in Turna's usage data, one in three shift types with set hours ends before the time it starts — in other words, it crosses midnight. Any method that does not allow for it is wrong a third of the time.

Your break comes off too

If your shift includes a break you do not work, those hours are not hours worked and so they do not count in full as night hours either.

The sensible approach is to take the break off the shift and spread the deduction proportionally: if you rest one hour out of eight, you work seven, and the night hours come down in the same proportion as the rest. A shift from 22:00 to 06:00 with an hour's break is seven hours worked and seven at night.

That is a convention, not a rule: whatever your collective agreement says about how the break is treated overrides any general calculation.

A method for checking it yourself

If you want to verify the count without relying on any app, the manual procedure is this:

1. Write down the start and end time of every shift in the month.
2. For each one, look at how much it overlaps the 22:00-06:00 band, treating it as one continuous eight-hour block that crosses midnight.
3. If the shift starts before 22:00, start counting at 22:00. If it ends after 06:00, stop counting at 06:00.
4. Add up the minutes and divide by sixty.

With three or four shifts it is doable. With twenty a month and a cycle that rotates, it is where people give up and end up trusting whatever the payslip says without being able to check it.

The night premium: what holds and what does not

It is worth being clear here, because a lot of confused information gets passed around.

What is common to everybody: the reference band, 22:00 to 06:00.

What is NOT common: how much those hours pay. The amount or the percentage of the night premium is set by your collective agreement, and it varies enormously between sectors and between regions. Two people working exactly the same night can be paid very different premiums and both be paid correctly under their own agreement.

So the only thing you can work out with certainty on your own is how many night hours you have worked. The amount comes from multiplying those hours by whatever your agreement says. If you do not have it to hand, look it up by the name of your sector and your region, or ask your works council.

How to keep track without doing it by hand

If your shift calendar knows the hours of each shift type, the count is automatic: the month's total hours, how many fall in the night band and how many on a bank holiday.

In Turna the monthly report separates those three figures and, if you also set your hourly rate and the premium that applies to you, it gives an estimate for the month. It does not replace your payslip: it is there so you can check it, which is exactly what almost nobody can do today.

If you work in private security, industry or nursing, the sectors with the most nights, the difference between keeping track and not keeping track is several hours a month.

Why it is worth keeping track

The practical reason is not distrust: it is that without a record of your own you have nothing to compare against. If the premium comes out differently one month, without your own hours you cannot tell whether you got it wrong, whether the rota changed or whether there is a mistake.

On top of that, having your hours split by type — ordinary, night and bank holiday — gives you something concrete to point at when it comes up, instead of a general impression that "I have done a lot of nights this month".

And for anyone who wants to go further: the same count shows whether nights are being shared out evenly among colleagues over the year, which is a far easier conversation to have with figures than without them.

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