How part-time pay is worked out
A part time salary calculator does one sum: the full-time salary for the job, multiplied by your share of the full-time week. Whether you call it a part time wage calculator or a part time pay calculator — weekly-paid staff often say “wage”, salaried staff say “salary” — the arithmetic is identical, and so is the rule underneath it: your hourly rate is the full-time rate for the job, unchanged. Only the hours are fewer.
From the annual figure, monthly pay is the total divided by 12 and weekly pay is the total divided by 52. The calculator shows all of these, plus a daily rate if you add your working days, and it prints the full calculation under the result so you can compare it line by line with an offer letter or a payslip. If you are going the other way — deciding how many hours you can afford to work — the reverse calculator starts from the pay you need.
Your rights as a part-time worker
Part-time pay is not a favour from the employer; it is a legal position. The Part-time Workers (Prevention of Less Favourable Treatment) Regulations 2000 say that a part-time worker must not be treated less favourably than a comparable full-time worker — someone doing the same or broadly similar work — purely because they work part time, unless the employer can justify the difference on objective grounds.
In practice that means:
- The same hourly rate for the same job, with pay, holiday and pension contributions scaled pro rata.
- Pro rata holiday — at least 5.6 weeks of your own working pattern, including a fair share of bank holidays.
- Access to the same benefits and training, scaled where scaling makes sense. A bonus or pension contribution is normally pro rata; access to a training course is not reduced at all.
- Overtime: a part-time worker does not usually have to be paid an overtime premium until they have worked beyond the full-time hours for the job, but the ordinary hourly rate applies to every hour worked.
If you believe you are being treated less favourably, you can ask your employer for a written statement of the reasons. ACAS publishes guidance on part-time workers' rights and can advise on disputes: acas.org.uk/part-time-workers. Holiday entitlement in detail is on GOV.UK.
Term-time only and school-based part-time roles have the extra paid-weeks step described on the teacher pro rata calculator page. Holiday figures for any part-time pattern are on the pro rata holiday calculator.
A four-day week: what you actually lose
The question behind most part-time calculations is what a shorter week really costs after tax — and it is less than the headline suggests, because the first £12,570 of pay is tax-free however you earn it. Take a £36,000 full-time job at 40 hours a week. Full time, the take-home pay is £29,439.60 a year after £4,686.00 income tax and £1,874.40 National Insurance. Drop to four days (32 hours) and gross pay falls by exactly 20%, to £28,800 — but tax falls to £3,246.00 and National Insurance to £1,298.40, so take-home pay is £24,255.60: a fall of £5,184.00, or 17.6%, not 20%. The tax system absorbs £2,016 of the £7,200 gross cut. Run your own salary through the take-home estimate above to see the same effect on your figures — the lower the salary, the stronger it is, because the personal allowance covers more of the pay.
Pensions: most part-time employees are auto-enrolled into a workplace pension on the same terms as full-time staff once they earn over £10,000 a year with one employer and are aged 22 or over. Your contribution is a percentage of your part-time pay, and your employer's contribution is pro rata in the same way. If you enter your pension percentage in the take-home estimate above, it is treated as salary sacrifice; check your scheme's basis if your figures differ slightly.
Rates and assumptions used — 2026/27
The take-home estimates on this page use the rates below. They are the standard rates for an employee paid a salary; your own tax code and circumstances may differ.
Income tax — England, Wales and Northern Ireland
| Band | Rate | Applies to |
|---|---|---|
| Personal allowance | 0% | The first £12,570 of income. The allowance falls by £1 for every £2 of income over £100,000, and reaches £0 at £125,140. |
| Basic rate | 20% | Taxable income up to £37,700 (income up to £50,270 with the full allowance). |
| Higher rate | 40% | Taxable income above £37,700, up to £125,140 of total income. |
| Additional rate | 45% | Total income over £125,140. |
Income tax — Scotland
Scottish taxpayers (your tax code starts with S) pay Scottish rates on employment income. The personal allowance and its taper are the same as the rest of the UK.
| Band | Rate | Income range |
|---|---|---|
| Starter rate | 19% | £12,571 – £16,537 |
| Basic rate | 20% | £16,538 – £29,526 |
| Intermediate rate | 21% | £29,527 – £43,662 |
| Higher rate | 42% | £43,663 – £75,000 |
| Advanced rate | 45% | £75,001 – £125,140 |
| Top rate | 48% | Over £125,140 |
National Insurance — employees (Class 1, UK-wide)
| Earnings | Rate |
|---|---|
| Up to £12,570 a year | 0% |
| £12,570 to £50,270 a year | 8% |
| Over £50,270 a year | 2% |
Assumptions
- Pension: any pension percentage you enter is treated as salary sacrifice — taken from your pay before tax and National Insurance are worked out. If your scheme works differently (for example, relief at source), your figures will differ slightly.
- Not included: student loan repayments, tax codes other than the standard personal allowance, Marriage Allowance, Blind Person's Allowance, benefits in kind, and any savings or dividend income. The estimate covers employment income only.
- Figures are annualised from the yearly thresholds, as most salary calculators present them; payroll works month by month, so a single payslip can differ by a few pence.
Last checked: October 2026. Sources: HMRC and GOV.UK for UK rates and National Insurance; Scottish bands from the Scottish Government Budget 2026-27 (Scottish income tax is set by the Scottish Parliament and administered with Revenue Scotland). This is general information, not financial advice.
Frequently asked questions
Part-time pay is the full-time salary multiplied by your fraction of the full-time week. If the job pays £36,000 full time at 40 hours and you work 20 hours, your fraction is 0.5 and your pay is £18,000 a year — at the same hourly rate of £17.31.
No. Under the Part-time Workers (Prevention of Less Favourable Treatment) Regulations 2000, a part-time worker must not be treated less favourably than a comparable full-time worker purely because they work part time, unless the treatment can be justified. A lower hourly rate for the same job is the clearest example of less favourable treatment.
Yes, in proportion. Every 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. Our holiday calculator works it out in days and hours.
If your hours are irregular, pay is usually based on your average or actual hours in each pay period rather than a fixed fraction, and holiday builds up at 12.07% of the hours you work. Use the irregular-hours mode on the holiday calculator for the holiday side of that arrangement.