Pro rata means “in proportion”. When pay or holiday is described as pro rata, the full-time amount is scaled down by the share of full-time work you do — so a person working half the full-time hours receives half the full-time salary, at exactly the same hourly rate.
The phrase comes from Latin and is used across UK employment contracts, job adverts and payroll. It answers a fairness problem: a part-time worker should be paid the same rate as a full-time colleague doing the same job, for the hours they actually work. Pro rata is the mechanism that keeps the rate equal while the totals differ. Almost every figure in part-time employment — salary, holiday, pension contributions, bonuses — is set this way.
Pro rata in salary
In a salary context, pro rata means the figure quoted is the full-time salary, and yours is the share of it matching your working week. The share is your hours divided by the full-time hours. Work 24 hours where full time is 40 and your share is 24 ÷ 40 = 0.6, so a £40,000 salary becomes £24,000. Work in days instead and the same share comes from your days divided by full-time days. The pro rata salary calculator does this sum and shows the monthly, weekly and hourly figures alongside the annual one.
Notice what does not change: the hourly rate. £40,000 at 40 hours a week is £19.23 an hour, and at 24 hours a week it is still £19.23 an hour. If a part-time offer works out at a lower hourly rate than the full-time rate for the same job, it is not a true pro rata figure, and it is worth questioning.
Pro rata in wages
For weekly-paid and hourly-paid work the idea is the same, applied to the wage packet rather than an annual salary. A full-time wage of £800 a week for 40 hours becomes £480 a week at 24 hours — the same £20 hourly rate throughout. Pro rata also appears in wages when someone starts or leaves mid-week or mid-month: they are paid for the fraction of the period they were employed, rather than the whole period.
What “per annum pro rata” means in a job advert
Job adverts often carry a line such as “£28,000 per annum pro rata”. “Per annum” simply means per year. Read together, the line means: £28,000 is the yearly salary for the full-time job, and the successful applicant, working part time, will receive the proportion of it that matches their hours. It does not mean you will be paid £28,000. Before applying, it is worth converting the line into real money: at 3 days out of 5, £28,000 per annum pro rata pays £16,800 a year. The calculator on our homepage does that conversion, and the reverse calculator works out the hours if you start from the pay you need.
Pro rata holiday
Holiday entitlement is pro rata in exactly the same way. Every UK worker is entitled to at least 5.6 weeks of paid holiday a year; a part-time worker receives 5.6 of their own working weeks. At 3 days a week that is 16.8 days, against 28 days for a 5-day week — the same proportion of the year off, measured fairly. Workers with irregular hours build holiday up at 12.07% of the hours they work. The holiday calculator covers both methods.
Pro-rata meaning in salary and wages
On a payslip, pro rata is the reason your gross pay is lower than the full-time salary for your job while your hourly rate matches it exactly. The figure printed is the full-time amount scaled by your contracted share of the week, and the same share is normally applied to holiday pay, overtime and pension contributions on that payslip.
In a job advert, the phrase points the other way: the salary shown is the full-time figure, and “pro rata” tells you the post is part time, so what you actually earn is the share that matches the hours advertised. Two adverts can quote the same salary and pay very different amounts once the fraction is applied. You will also see it written “pro rated”, without the hyphen, in older adverts and American documents — it means exactly the same thing.
Three short examples
| Situation | Working | Result |
|---|---|---|
| Salary: £40,000 full time, working 24 of 40 hours | £40,000 × (24 ÷ 40) | £24,000 a year |
| Holiday: 28 days full time, working 3 of 5 days | 28 × (3 ÷ 5) | 16.8 days a year |
| Advert: £28,000 per annum pro rata, 3 of 5 days | £28,000 × (3 ÷ 5) | £16,800 a year |
Glossary
| Term | What it means |
|---|---|
| Pro rata | In proportion. The full-time amount multiplied by your share of the full-time working week. |
| Per annum | Per year. A salary quoted per annum is a yearly figure, before tax. |
| FTE | Full-Time Equivalent. Your share of a full-time job written as a decimal: 0.6 FTE is 60% of full time. |
| Prorated | The past tense of the same idea, common in American English: an amount that has been scaled in proportion. |
For the full method with more examples, see how to work out pro rata salary. Sources for the holiday rules on this page: GOV.UK — holiday entitlement rights and ACAS — part-time workers.
Frequently asked questions
It means your wages are paid in proportion to the hours you work, at the same hourly rate as a full-time worker in the same job. If the full-time wage is £800 a week for 40 hours and you work 20 hours, your pro rata wage is £400 a week.
It means the salary for a part-time version of a job, worked out as a share of the full-time salary. A post advertised at “£30,000 pro rata” pays the full £30,000 only if worked full time; at 3 days out of 5 it pays £18,000 a year.
“Per annum” means per year, and “pro rata” means in proportion. Together they mean: this is the yearly full-time salary, and you will receive the share of it that matches your hours. The advert is quoting the full-time yearly figure, not necessarily the amount you will be paid.
Pro rata pay is any pay calculated in proportion to hours worked or time served — a part-time salary, pay for a part-month when you start or leave a job, or a bonus scaled to your working pattern. In each case a full amount is multiplied by a fraction less than one.
In a salary context it means the stated salary is the full-time figure and your actual salary is the proportion of it that matches your working week. Your hourly rate is unchanged; the annual total falls because the hours fall.