ProRata CalculatePart Time Salary Calculator — See the Pay Before You Agree the Hours
See what a part-time pattern pays before you agree to it. Enter the full-time salary and your hours to compare annual, monthly and weekly pay.
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.
Deciding whether the drop is affordable
The gross drop is easy to see; the real question is the take-home drop, and it is almost always smaller than people fear. Because your personal allowance stays at £12,570 and National Insurance is charged on what you actually earn each month, moving from full time to three days typically cuts gross pay by 40% but take-home pay by noticeably less. Run your current pattern and your proposed pattern through the calculator and compare the take-home panel, not just the headline salary — that comparison, printed out, is also a persuasive thing to take into a flexible-working discussion, because it shows you have costed the change properly.
Do remember the costs that do not shrink: rent, council tax and most subscriptions stay exactly where they were. The patterns that work best financially are usually the ones where the saved day also saves money — a day of childcare not bought, a commute not made — and it is worth totalling those savings alongside the pay figures before deciding.
Two patterns people ask about most
Four days instead of five. On a £36,400 full-time salary with a 37.5-hour week, four days means 30 hours, a fraction of 0.8, and a salary of £29,120 — £2,426.67 a month. The single dropped day costs £7,280 a year gross; after tax and National Insurance at 2026/27 rates the take-home cost is smaller, which the panel above will show for your own figures.
School hours only. A £29,750 role at 37.5 hours, worked at 18.75 hours across five short days, pays £14,875. The trap in school-hours posts is the daily rate: if your 18.75 hours are spread over five days, your “day” is 3.75 hours, and any daily figure quoted by payroll should be built from your hours, not from a standard day. The hours mode of the calculator handles this correctly; a days-based calculation would overstate your day length and understate nothing else — which is why it slips through unnoticed.
Your rights, briefly
The Part-time Workers (Prevention of Less Favourable Treatment) Regulations give you the right not to be treated worse than a comparable full-time colleague simply because you work part time, with pro rata as the measuring stick. In practice that covers hourly pay, leave, pension access, training and selection for redundancy. Where treatment differs, the employer needs an objective business justification. Acas publishes a plain-English summary of the rules, and Citizens Advice can check a specific situation free of charge. If a payslip looks wrong, start with the fraction: nine times out of ten the error is there, and it is the easiest thing for payroll to fix.
Once your pay is settled, run the same fraction through the holiday calculator — leave is where part-time arrangements most often quietly lose value — and read our guide to part-time holiday entitlement before your first leave year ends.
Questions people ask
From the full-time salary for the same role, scaled by your share of the full-time week. A £29,750 role worked at 18.75 of 37.5 hours pays half: £14,875. There is no separate part-time pay scale in law — the proportion is the whole mechanism.
Yes, in percentage terms. A 3% rise for the department should be a 3% rise on your pro rata salary too. What you should not accept is a rise applied only to the full-time figure while your fraction is quietly recalculated downwards — check both numbers after every April pay review.
Contracts vary, but a common and fair arrangement is plain time until you pass the full-time weekly hours, then the full-time overtime rate beyond that point. Whatever your contract says, hours up to the full-time threshold should never be paid below your normal hourly rate.
You have a legal right to request flexible working from day one of employment, and your employer must handle the request reasonably and decide within two months. They can refuse only for recognised business reasons. A refusal of the request is different from a dispute about pay — the pro rata principle itself is not optional once part-time hours are agreed.
Most allowances follow the same fraction as salary: a £2,400 annual allowance becomes £1,440 at 0.6 FTE. Some flat-rate payments, such as certain on-call retainers, are paid in full regardless of hours. Your contract should say which is which — if it is silent, ask before you sign, not after your first payslip.
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.