How to Work Out Pro Rata Salary
A clear, step-by-step guide with formula, examples, and free calculator
The Pro Rata Salary Formula Explained
Working out your pro rata salary requires a simple proportional calculation. Take the full-time equivalent salary for the role and multiply it by the fraction of hours you work compared to full-time. This gives your gross annual pay before any tax deductions.
For instance, a role paying £28,000 for 37.5 hours per week, where you work 22.5 hours: £28,000 × (22.5 ÷ 37.5) = £28,000 × 0.6 = £16,800 per year.
Step-by-Step Walkthrough
Find the full-time salary
Check your contract or the job advert. Look for the figure followed by "pro rata" or "FTE." This is the starting point for your calculation.
Confirm the standard full-time hours
Ask HR or check your organisation's policy. Common UK standards are 35, 37.5, or 40 hours per week. Using the wrong figure will give an incorrect result.
Check your contracted hours
Your employment contract specifies your weekly hours. Include any regular fixed hours but exclude variable overtime.
Divide and multiply
Divide your hours by full-time hours to get the FTE ratio. Multiply the full-time salary by this ratio. The result is your annual gross pro rata salary.
Real-World Examples
| FT Salary | FT Hours | Your Hours | Pro Rata |
|---|---|---|---|
| £22,000 | 37.5 | 15 | £8,800 |
| £26,000 | 37.5 | 22.5 | £15,600 |
| £33,000 | 36 | 28 | £25,667 |
| £40,000 | 40 | 24 | £24,000 |
For more complex scenarios involving term-time adjustments, use our term-time calculator. To convert your result into take-home pay, try the take-home pay tool.
Quick Summary: How to Work Out Pro Rata Salary
If you're short on time, here's what you need to know about how to work out pro rata salary:
- What it means: How to Work Out Pro Rata Salary involves calculating pay or entitlement proportionally based on the ratio of hours or time worked versus the full-time equivalent.
- The formula: Full-Time Amount × (Your Hours ÷ Full-Time Hours) = Your Pro Rata Amount
- Who needs it: Part-time workers, term-time staff, teachers, job-sharers, and anyone on reduced hours.
- UK law: Under the Part-time Workers Regulations 2000, part-time employees have the right to be treated no less favourably than comparable full-time workers.
Worked Example: How to Work Out Pro Rata Salary
Let's work through a practical example of how to work out pro rata salary. A marketing coordinator role advertises a full-time salary of £28,000 for 37.5 hours per week. You're offered the position at 25 hours per week.
Step 1 — Find your FTE ratio: 25 ÷ 37.5 = 0.667 (66.7%)
Step 2 — Calculate pro rata salary: £28,000 × 0.667 = £18,667 per year
Step 3 — Monthly breakdown: £18,667 ÷ 12 = £1,556 gross per month
Step 4 — Holiday entitlement: 28 days × 0.667 = 18.7 days pro rata
After income tax and NI (2025/26 rates), your monthly take-home would be approximately £1,377. Use our pro rata calculator above to check your own figures.
Tips for How to Work Out Pro Rata Salary
- Always use gross salary: Enter the salary before tax and deductions — the calculator works with gross figures.
- Check your contract: Your employment contract should state your full-time equivalent hours. Common UK standards are 35, 37, 37.5, and 40 hours per week.
- Know your rights: Under the Part-time Workers Regulations 2000, part-time employees must receive the same hourly rate, holiday entitlement (pro rata), and benefits as full-time colleagues.
- Tax personal allowance: For 2025/26, the first £12,570 of earnings is tax-free. If your pro rata salary falls below this, you pay no income tax at all.
- National Insurance: Employee NI is 8% on earnings between £12,570 and £50,270 (2025/26 rates). Check HMRC NI rates for the latest figures.
Pro Rata Holiday Entitlement
Under the Working Time Regulations 1998, all UK workers are entitled to a minimum of 5.6 weeks' paid holiday per year (28 days for full-time). If you work part-time, your entitlement is calculated pro rata based on your actual hours or days worked.
| Days Worked/Week | FTE Ratio | Statutory Days/Year | Bank Holidays (pro rata) |
|---|---|---|---|
| 5 days (full-time) | 1.0 | 28 days | 8 days |
| 4 days/week | 0.8 | 22.4 days | 6.4 days |
| 3 days/week | 0.6 | 16.8 days | 4.8 days |
| 2.5 days/week | 0.5 | 14 days | 4 days |
| 2 days/week | 0.4 | 11.2 days | 3.2 days |
Holiday entitlement is always rounded up — never down — when the result is not a whole number, per ACAS guidance on holiday entitlement. Bank holidays may be included in or added on top of your statutory 28 days, depending on your contract.
All calculations on this page follow ACAS pro rata pay guidelines and are consistent with the UK Employment Rights Act 1996. Tax figures use HMRC 2025/26 rates. The April 2025 National Living Wage of £12.21/hour is applied where relevant.
Further Reading
For more help with how to work out pro rata salary, explore our free UK tools. You may also find these useful: term-time salary calculator, overtime calculator, holiday pay guide.
Last updated: February 2026. Verified against HMRC 2025/26 tax rates and April 2025 National Living Wage (£12.21/hour).
Frequently Asked Questions
Pro rata means "in proportion." In employment, it refers to adjusting a full-time salary proportionally based on the number of hours, days, or weeks actually worked compared to a full-time equivalent role.
Divide the full-time salary by full-time hours, then multiply by your actual hours. For example: £30,000 ÷ 37.5 hours × 25 hours = £20,000 pro rata.
Pro rata salary is usually calculated before holiday pay. Your holiday entitlement is also pro-rated — part-time workers get 5.6 weeks holiday pro rata, calculated proportionally to hours worked.
Not exactly. Pro rata is the method used to calculate part-time salary. It ensures part-time workers receive the proportional equivalent of the full-time rate, maintaining fairness under UK employment law.