Plain English guide · checked 21 August 2026
What does pro rata mean?
Pro rata is Latin for “in proportion”. When a UK job advert says “£30,000 pro rata”, the £30,000 is the full-time salary and you get the share that matches your hours. Work half the full-time hours, get half the pay. That is the whole idea.
The word turns up on payslips and contracts too, and it always means the same thing: a full amount scaled down to the portion of time you actually work. Below is what that looks like in pounds, where else pro rata applies, and how it affects your holiday.
Pro rata in a job advert: a worked example
Say the advert reads “£30,000 pro rata, 25 hours per week” and the company’s full-time week is 37.5 hours. Your salary is the full-time figure multiplied by your hours and divided by the full-time hours:
£30,000 × 25 ÷ 37.5 = £20,000 a year
That is £1,666.67 a month before tax. The hourly rate behind both figures is the same: £30,000 ÷ 52 ÷ 37.5 = £15.38.
Two things to check before you rely on the sum. First, the full-time hours: 37.5 and 40 are both common in the UK, and the difference changes the result. Second, whether the advert quotes the full-time salary or your actual salary; adverts are not always careful about it. If you want the monthly, weekly and hourly figures done for you, the pro rata pay calculator on our home page does the maths as you type.
£30,000 pro rata at different hours
Here is the same £30,000 full-time salary (37.5-hour week) scaled to common part-time patterns. Notice the hourly rate never moves.
| Hours per week | The sum | Pro rata salary |
|---|---|---|
| 37.5 (full-time) | 30,000 × 37.5 ÷ 37.5 | £30,000 |
| 30 | 30,000 × 30 ÷ 37.5 | £24,000 |
| 25 | 30,000 × 25 ÷ 37.5 | £20,000 |
| 20 | 30,000 × 20 ÷ 37.5 | £16,000 |
Where pro rata shows up
Part-time salaries are the obvious case, but the same in-proportion rule appears in several other places:
- Holiday entitlement. Everyone gets 5.6 weeks of statutory leave, but a week means your own working week. Three days a week gives 16.8 days of holiday rather than 28.
- Starting or leaving mid-month. Your first and last payslips usually cover only the days you were employed, worked out as a proportion of the monthly salary.
- Term-time contracts. School support staff and similar roles are paid for the weeks they work plus holiday, with the total often spread over 12 equal monthly payments.
- Bonuses and benefits. An annual bonus pot or benefit allowance is often scaled to your hours, or to the months you were employed during the bonus year.
One thing pro rata does not usually touch: expenses, mileage and one-off payments for a specific piece of work. Those are paid in full because they do not depend on your weekly hours.
Pro rata holiday
Holiday is where pro rata catches people out. Part-time workers do not get less holiday in law; they get the same 5.6 weeks, measured in their own working days. Multiply your days per week by 5.6: four days a week gives 22.4 days, two days a week gives 11.2. The statutory figure is capped at 28 days for everyone.
If your hours vary from week to week, on a zero-hours or casual contract, holiday accrues at 12.07% of the hours you work instead. We cover that in detail in our guide to zero-hours contract holiday entitlement. For a regular pattern, the holiday entitlement calculator gives you the exact figure in days or hours.
Pro rata meaning: common questions
Is pro rata legal?
Yes. Paying part-time staff in proportion to their hours is exactly what UK law expects. The Part-time Workers Regulations 2000 say part-time staff must not be treated less favourably than comparable full-time colleagues, and pro rata pay is the standard way to meet that: the same hourly rate, scaled to fewer hours.
Does pro rata affect my hourly rate?
No. The hourly rate stays the same; only the number of paid hours changes. £30,000 for a 37.5-hour week works out at £15.38 an hour whether you do 37.5 hours or 20. If a part-time worker is put on a lower hourly rate for the same job, that is not pro rata and it may be unlawful less favourable treatment.
What does "per annum pro rata" mean?
Per annum is Latin for "per year", so "£30,000 per annum pro rata" means the full-time yearly salary is £30,000 and your actual salary is that figure scaled to your hours. On 25 hours against a 37.5-hour full-time week you would earn £20,000 a year.
How does pro rata work for salaried versus hourly staff?
Salaried staff have an annual figure that gets scaled: full-time salary times your hours divided by full-time hours. Hourly staff do not need scaling because they are simply paid for the hours they work. For hourly staff the pro rata idea shows up in holiday instead, which accrues in proportion to hours worked.
Does pro rata apply if I start or leave a job mid-month?
Usually, yes. Most employers pay a proportion of the monthly salary based on the days you were actually employed that month, often calendar days in the month or your working days in it. The method should be in your contract or staff handbook, and it can change the figure by a few pounds either way.
Got a real offer to check? Put the numbers into the pro rata pay calculator and see the annual, monthly, weekly and hourly figures side by side.