ProRata CalculatePro Rata Salary Calculator — Calculate Pro Rata Salary Exactly
Work out your pro rata salary from a full-time wage. Enter the full-time pay and your hours or days to see what you will actually be paid, before and after tax.
Pro Rata Salary Calculator
Type the full-time figures from the advert or contract, then your own pattern. The answer updates as you type.
What lands in your bank account?
Gross pay is only half the story. Add your tax region and any pension contribution and this estimate applies 2026/27 Income Tax and National Insurance to the pro rata figure above. Pension is treated as salary sacrifice, so it comes off before tax and National Insurance are worked out.
Estimated take-home: — a year
| Full-time version | Your pattern | |
|---|---|---|
| Gross pay | — | — |
| Income Tax | — | — |
| National Insurance | — | — |
| Take-home | — | — |
Breakdown of your pattern — gross —, pension —, tax —, National Insurance —, leaving — a month and — a week. Student loans, benefits in kind and other deductions are not included.
The formula, once and for all
Every pro rata salary calculation on this site, and in every payroll office, reduces to one line: your pay = full-time salary × (your hours ÷ full-time hours). Nothing else is hiding in it. There is no separate part-time tax rate, no penalty for working fewer days, and no rounding convention that should cost you more than a few pence a year. When a figure from an employer disagrees with yours, the disagreement always sits in one of the three inputs: the full-time salary they used, the hours they used, or the fraction itself. Ask for all three, in writing, and the mistake usually reveals itself.
Where a contract counts days rather than hours — common in schools, surgeries and rostered services — swap hours for days in the same line. A three-day post in a five-day workplace carries a fraction of 0.6 whichever way you count it, provided your working days are the same length as full-time days. If your days are shorter, hours are the honest measure, and you should insist the fraction is built from hours.
Two examples with the working showing
Example one — the £30,000 question. A council advert reads “£30,000 per annum, pro rata, 3 days per week”. The fraction is 3 ÷ 5 = 0.6. Annual pay is £30,000 × 0.6 = £18,000, which is £1,500 a month and £346.15 a week. The hourly rate, assuming a 37.5-hour full-time week, is £30,000 ÷ (37.5 × 52) = £15.38 — and £15.38 is exactly what the part-time post should also pay per hour.
Example two — hours, not days. A warehouse team leader post pays £38,750 full time at 40 hours. You negotiate 24 hours. The fraction is 24 ÷ 40 = 0.6, the salary is £23,250, and the monthly figure is £1,937.50. Notice both examples land on 0.6 by different routes; payroll software does not care which route you took, and neither should an offer letter.
For the £25,000 version of the same question — £25,000 pro rata at three days is £15,000 a year — and three further examples including a term-time one, see the step-by-step guide. If instead you know the pay you need and want the hours that produce it, the reverse calculator works the formula backwards.
Gross is not what arrives in your account
The take-home panel under the calculator applies 2026/27 Income Tax and National Insurance to your pro rata result. Two things surprise people. First, your personal allowance is not reduced because you work part time — the same £12,570 tax-free allowance applies, which is why part-time pay often keeps a bigger share of each pound than the full-time version. Second, National Insurance is calculated per pay period on what you actually earn, so a lower monthly salary can mean a noticeably lower NI bill than a simple proportion would suggest. Treat the estimate as a planning figure: student loan repayments, pension choices and benefits in kind all move the final number, and your payslip remains the record that counts.
Questions people ask
Divide your weekly hours by the full-time weekly hours, then multiply the full-time salary by that fraction. On this page: £38,750 × (24 ÷ 40) = £23,250 a year. The calculator calls this “by hours” mode; “by days” mode does the same thing with days when your contract counts days instead.
Three days out of five is a fraction of 0.6, so £30,000 pro rata at three days pays £18,000 a year, £1,500 a month before deductions. At two days it is £12,000, and at four days £24,000. Searches like “30000 pro rata” are popular precisely because adverts rarely do this sum for you.
No — prorated is the US spelling of the same proportion, and a salary prorated calculator performs the identical calculation. UK employers, contracts and the GOV.UK website all use “pro rata”, so that is the wording used across this site, but the numbers would match either way.
Small differences usually come from how your employer treats the month you started or left, pension contributions taken before the monthly figure you are comparing, or a pay rise part-way through the year. Compare annual gross figures first; if those disagree, ask payroll for their fraction and their full-time salary — one of the two will differ from yours.
Your pension contributions are normally the same percentage of your actual, reduced salary, and many employers match on the same terms as full-time staff. What changes is the cash amount, because the percentage is applied to a smaller salary. Check whether your scheme calculates contributions on actual pay or on the full-time equivalent — schemes differ.
Calling it pro rata would be misleading. Part-time workers are protected by the Part-time Workers Regulations, which rest on the principle that part-time staff should not be treated less favourably, pro rata, than comparable full-time staff. A lower hourly rate for the same job is the classic breach — raise it in writing if you spot it.
Rates used: UK tax year 2026/27 · Last reviewed: October 2026. Calculations run in your browser — nothing you type is sent anywhere or stored by us.