Pro rata salary calculator
Job adverts often quote a full-time salary 'pro rata'. Enter the advertised salary and your hours to see what you'll actually earn.
How pro rata pay works
The formula is simple:
Pro rata salary = full-time salary × (your hours ÷ full-time hours)
Full-time hours vary between employers. 37.5 hours (five 7.5-hour days) and 40 hours are the most common, while many public sector and NHS jobs use 37.5. The job advert or contract should say what full-time means.
Pro rata examples on a £30,000 salary
| Hours a week (of 37.5) | Pro rata salary | A month |
|---|---|---|
| 15 | £12,000 | £1,000 |
| 18.75 (half time) | £15,000 | £1,250 |
| 22.5 (3 days) | £18,000 | £1,500 |
| 30 (4 days) | £24,000 | £2,000 |
Your rights as a part-time worker
By law, part-time workers must not be treated less favourably than comparable full-time workers. That means the same hourly rate, pro rata holiday, pension access, and the same access to training and promotion.
Frequently asked questions
What does pro rata mean on a salary?
Pro rata means 'in proportion'. A pro rata salary is the full-time salary scaled down to the hours or days you work. If a full-time job pays £30,000 for 37.5 hours a week and you work 22.5 hours, you'll earn 22.5 ÷ 37.5 × £30,000 = £18,000.
How do I calculate pro rata salary by days?
Divide the days you work by the full-time days and multiply by the full-time salary. Working 3 days of a 5-day week on a £35,000 salary gives 3 ÷ 5 × £35,000 = £21,000.
Is holiday pro rata too?
Yes. Part-time workers are entitled to the same 5.6 weeks of paid holiday as full-time workers, which in days works out proportionally. Someone working 3 days a week gets 5.6 × 3 = 16.8 days. Use our holiday entitlement calculator to check yours.
Is a pro rata salary before or after tax?
Pro rata salaries are quoted before tax. Because Income Tax and National Insurance don't scale in a straight line, your take-home pay will be a bigger share of the full-time take-home than your gross pay is. Use our salary calculator to see your take-home pay.
Last checked 5 October 2026.