How to calculate holiday accrual for hourly staff [calculator]

(Updated: 29/02/24)

In the UK, part-time staff must be treated comparably to full-time workers in the same role. That means the same rates of pay, getting access to the same types of training, and getting paid annual leave at the same rate.

If the employee is working regular hours, it’s easy to work out the holiday they’re entitled to. For example, if they work three days instead of the typical five, they’re entitled to 60% of the holiday allowance of their full-time colleagues, including bank holidays.

But if staff work variable hours each week, things start to get a little more complicated.

Here, staff ‘accrue’ holiday for the hours they’ve worked, and it’s added onto their total holiday allowance, usually at the end of each pay period.

We built this quick annual leave calculator to help you work out the number of hours of holiday entitlement your hourly staff with variable hours might accrue:

Here's a handy calculator:

Holiday accrual calculator: FAQs

How should this calculator be used?

You can use this calculator to work out the holiday accrual of hourly, part-time workers who work variable hours or are on zero-hours contracts. The calculator works by adjusting the typical annual leave entitlement of full-time staff at your business and turning it into an accrual rate.

You then enter the number of hours the employee has worked over the period — for example, the pay period — into the calculator.

Then, it works out leave entitlement accrued over the period. You can enter this number into your leave management spreadsheet or system — just make sure you record which period of work it relates to.

Why is 12.07% the default rate for holiday accrual?

We use 12.07% as the default accrual rate in this calculator because it reflects the statutory minimum annual leave allowance in the UK.

Here’s how that ‘12.07%’ rate is calculated. 5.6 weeks is the usual holiday allowance for full-time workers, out of 52 weeks. That means employees accrue their holiday in the remaining 46.4 weeks of the year (52 - 5.6 weeks). 5.6 divided by 46.4 is 0.1207, or 12.07%, so workers accrue holiday at a rate of just over 12%. For every 100 hours worked, 12.07 hours are accrued as annual leave entitlement.

Does the 12.07% rule always apply?

No — there are two other things to think about.

First, you might offer additional leave on top of the statutory minimum. The calculator allows for this and adjusts the accrual rate accordingly.

Secondly, if staff can’t potentially work every week, for example, due to working term times only, the calculation is different again. For example, if they can only work 40 weeks a year, the holiday will accrue at a rate of 5.6/(40-5.6) = 16.2%.

It gets a bit more complicated than this, but we wanted to keep this calculator as straightforward as possible.

What about bank holidays?

Part-time staff should receive bank holidays as part of their entitlement on a proportional basis — it’s included within the accrual rate.

This article isn’t legal advice. It’s just for general information purposes. If you’re unsure about how holiday accrual rules apply to your specific case, contact a legal expert.