Key facts
- Pro rata scales a full-time salary to the hours you actually work
- On £35,000 for a 37.5 hour week, three days (22.5 hours) pays £21,000 a year
- Statutory holiday is 5.6 weeks, giving 16.8 days for a three-day week
- From 1 April 2026 the National Living Wage for ages 21 and over is £12.71 an hour
Once you know your pro-rata salary, see what reaches your bank in how to read your payslip guide and the bands behind it in income tax bands guide.
| Working pattern | Weekly hours | Pro-rata salary | Paid holiday |
|---|---|---|---|
| 5 days (full time) | 37.5 | £35,000 | 28 days |
| 4 days | 30 | £28,000 | 22.4 days |
| 3 days | 22.5 | £21,000 | 16.8 days |
| 2 days | 15 | £14,000 | 11.2 days |
Holiday is 5.6 weeks pro-rated by days worked. Source: GOV.UK holiday entitlement, WhatsUK calculation, June 2026.
To work out a pro-rata salary, divide the full-time salary by the full-time hours to get an hourly rate, then multiply by your weekly hours and by 52. For a £35,000 salary over a 37.5 hour week, that is £17.95 an hour, so a 22.5 hour week pays about £21,000 a year. The same logic scales holiday: 5.6 weeks full time becomes 16.8 days for someone working three days a week.
Whatever the pro-rata figure, it cannot drop your effective hourly pay below the legal minimum. From 1 April 2026 the National Living Wage for workers aged 21 and over is £12.71 an hour, with £10.85 for ages 18 to 20 and £8.00 for under 18s and apprentices. Always check that a pro-rata offer clears the minimum for your age.
Check the take-home on any salary with the contractor take home calculator.
The Pro-Rata Formula
There are two versions depending on whether you are calculating for days worked per week or for part of a year.
Days per week version:
Pro-rata salary = (FTE salary divided by full-time days per week) x actual days worked per week
Part-year version:
Pro-rata salary = (FTE salary divided by 365) x number of days in the employment period
Or for weeks: (FTE salary divided by 52) x actual weeks worked
Worked Examples
Example 1: Part-Time, 3 Days a Week
- FTE salary: £35,000 per year (5 days, 37.5 hours)
- Pro-rata days: 3 out of 5
- Pro-rata salary: £35,000 divided by 5 multiplied by 3 = £21,000 per year
Example 2: Mid-Year Joiner, Starting 1 October
- FTE salary: £40,000 per year
- Months remaining in tax year (October to April = 6 full months + part of October, approximately 182 days)
- Pro-rata salary for tax year: £40,000 divided by 365 multiplied by 182 = approximately £19,945
The employer's payroll will divide the £40,000 annual salary into monthly amounts from the start date. Each payslip shows the standard monthly amount (£3,333.33), but year-end P60 figures will reflect only the months worked.
Example 3: Fixed-Term 6-Month Contract
- FTE annual equivalent: £28,000
- Duration: 6 months (exactly half the year)
- Pro-rata earnings: £14,000
Pro-Rata Calculator
Calculate your precise pro-rata salary for any start date, end date, or days-per-week pattern. Updated for 2026/27.
Common Pro-Rata Salary Table: £35,000 FTE
| Days Worked per Week | Weekly Hours | Pro-Rata Annual Salary | Pro-Rata Monthly |
|---|---|---|---|
| 5 days (full-time) | 37.5 | £35,000 | £2,916.67 |
| 4 days | 30 | £28,000 | £2,333.33 |
| 3 days | 22.5 | £21,000 | £1,750 |
| 2 days | 15 | £14,000 | £1,166.67 |
Pro-Rata Tax and National Insurance
Your pro-rata salary is your actual annual income for HMRC purposes. The personal allowance (£12,570) and tax bands apply to your actual earnings, not the FTE equivalent.
This means a part-time worker on £21,000 (3 days) pays income tax on £21,000 minus £12,570 = £8,430, at 20%, which is £1,686 per year. The full-time equivalent on £35,000 pays tax on £22,430 at 20%, which is £4,486. The part-time worker benefits from paying a proportionally smaller income tax bill.
NI works the same way. The thresholds apply to actual earnings, so part-time workers earning below £12,570 per year pay no NI.
Expert Tip
If you work part-time and your annual earnings fall below £12,570, you will not pay income tax or NI. However, you may want to make voluntary NI contributions to protect your state pension record if your earnings are below the lower earnings limit (£6,396 for 2026/27). Each qualifying year of NI contributions builds toward the full state pension (currently requiring 35 qualifying years).Pro-Rata Holiday Entitlement
UK employment law provides a minimum of 5.6 weeks of paid holiday per year for full-time workers (28 days including bank holidays). Part-time workers receive the same entitlement proportionally.
Formula: Pro-rata holiday = 5.6 weeks multiplied by (actual days per week)
| Days per Week | Minimum Holiday Entitlement (Days) |
|---|---|
| 5 | 28 days |
| 4 | 22.4 days |
| 3 | 16.8 days |
| 2 | 11.2 days |
| 1 | 5.6 days |
Employers may round up, but rounding down is not permitted. Some contracts include more than the statutory minimum (28 days). Pro-rating applies to contractual entitlement in the same proportional way.
For mid-year starters, holiday entitlement is also pro-rated based on the proportion of the year worked. Starting on 1 October means working approximately half the year (26 weeks out of 52), so the holiday entitlement is approximately half the annual allowance.
Pro-Rata and Statutory Maternity Pay
Statutory Maternity Pay (SMP) is based on average weekly earnings over an 8-week reference period. For a part-time employee, average weekly earnings reflect actual hours worked. If the reference period falls after a reduction in hours (for example, after moving from full-time to part-time), SMP will be calculated on the lower earnings. Employees sometimes time maternity leave carefully to maximise the reference period earnings.
National Minimum Wage and Pro-Rata
Pro-rata calculations must always result in an effective hourly rate at or above the National Minimum Wage. From 1 April 2026, the rates are:
| Age Group | Hourly Rate |
|---|---|
| 21 and over (National Living Wage) | £12.71 |
| 18 to 20 | £10.85 |
| Under 18 | £8.00 |
| Apprentice | £8.00 |
A part-time salary must be checked against actual hours. A 3-day week at £21,000 per year represents approximately 1,170 hours (3 days x 7.5 hours x 52 weeks). At £21,000 divided by 1,170 hours = £17.95 per hour, well above the minimum wage for an adult worker.
Related Calculators
Frequently Asked Questions
Pro rata means a full-time salary adjusted in proportion to the hours you actually work. A job advertised at £35,000 pro rata does not pay £35,000 unless you work full time. If you work three days of a five-day week, you receive three-fifths, which is £21,000. It simply scales pay to your hours.
Divide the full-time salary by the full-time weekly hours to get an hourly rate, then multiply by your weekly hours and by 52. For £35,000 over 37.5 hours that is £17.95 an hour, so a 22.5 hour week is about £21,000 a year. You can also just multiply by your share of full-time hours.
Statutory holiday is 5.6 weeks, which is 28 days for a five-day week. Part-time workers get the same 5.6 weeks, but it is fewer days because their week is shorter. Someone working three days a week gets 5.6 times 3, which is 16.8 days of paid holiday a year.
Yes. The pro-rata figure is your actual annual salary for your hours, before tax and National Insurance. The full-time headline figure is only a reference point. So a £35,000 pro-rata role worked three days a week pays you £21,000 gross, which is then taxed like any other salary of that size.
For starting or leaving partway through a year, you scale by time as well as hours. Divide the annual salary by 365 and multiply by the number of days employed. So someone on £35,000 who works half the year receives about £17,500, adjusted further if they are also part time.
Your pay is lower, so percentage-based contributions are lower in pounds, but the rules are the same. Auto-enrolment still applies if you earn over £10,000, and holiday, sick pay and other entitlements are scaled to your hours rather than removed. Part-time workers have the same employment rights as full-time staff.
No. Once you divide the pro-rata salary by your actual hours, the resulting hourly rate must meet the legal minimum. From April 2026 that is £12.71 an hour for ages 21 and over. If a pro-rata offer works out below the minimum for your age, the employer must increase it.
They are two sides of the same calculation. Pro rata takes a full-time salary down to your hours, while full-time equivalent, or FTE, scales your part-time salary up to show what it would be full time. A £21,000 salary for three days a week has a full-time equivalent of £35,000.
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James Hartley is a Chartered Management Accountant (CIMA) with more than eight years of experience in UK tax, payroll and compliance. He holds a BSc in Finance and Economics from the University of Manchester and spent his early career at a Big 4 accounting firm. He founded WhatsUK to build free UK financial calculators and guides verified against official HMRC sources. He authors every calculator and article on WhatsUK.
Sources & Official References
- GOV.UK: Part-time workers' rights- Legal protections for part-time employees
- GOV.UK: National Minimum Wage rates- April 2026 minimum wage rates by age
- GOV.UK: Holiday entitlement- Statutory holiday rules including pro-rata
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Disclaimer: This calculator provides estimates based on standard HMRC rates for 2026/27. Results may vary based on individual circumstances. This is not financial advice. Always consult a qualified accountant or CIMA-qualified financial adviser for personal tax matters.