Pro-Rata Salary Calculator
Our pro rata calculator converts a full-time annual salary to the correct part-time or part-year equivalent. Whether you are starting a new job mid-year, negotiating a part-time arrangement, returning from maternity leave, or simply checking that your pro rata offer is fair, this calculator gives you the accurate figure instantly.
Pro-Rata Salary Calculator
Calculate your pro-rata salary for part-time hours, or work out your pay for a partial period.
How Pro Rata Salary Is Calculated
Pro rata means “in proportion.” A pro rata salary is calculated by dividing the full-time equivalent (FTE) annual salary by the total working hours or weeks in a full-time year, then multiplying by the hours or weeks you will actually work.
For part-time hours: if a full-time role pays £36,000 for 37.5 hours per week and you work 25 hours, your pro rata salary is £36,000 × (25 ÷ 37.5) = £24,000 per year. For part-year employment: if you join on 1 October and the annual salary is £42,000, you work 26 weeks of a 52-week year and your pro rata pay is £42,000 × (26 ÷ 52) = £21,000 for that tax year.
Part-Time Rights and Equal Pay
The Part-Time Workers (Prevention of Less Favourable Treatment) Regulations 2000 give part-time employees the right to the same pay, benefits, and terms as comparable full-time colleagues, on a pro rata basis. This includes holiday entitlement (28 days full-time becomes 18.67 days at 25 hours per week), sick pay, pension contributions, and contractual bonuses.
Employers cannot offer a lower hourly rate simply because a role is part-time. If you believe your part-time equivalent pay is unfair compared to a full-time colleague doing the same work, you have the right to request a written statement of reasons and may have a case for tribunal if the difference cannot be objectively justified.
Frequently Asked Questions
Yes. Both your pension contributions and your employer’s contributions are typically based on your actual pro rata salary. If your employer matches contributions as a percentage of salary, the absolute amount contributed will be lower — but the percentage remains the same as a full-time colleague. See our Pension Calculator to model long-term growth on any contribution level.
Your tax code reflects your Personal Allowance (£12,570) regardless of whether you work full or part time. The Personal Allowance is applied monthly in proportion to your actual earnings — if your pro rata income is £15,000, you pay 20% tax only on £2,430. Many part-time workers pay no income tax at all if earnings fall below £12,570.
Yes. Employers sometimes pay above the strict pro rata equivalent for specialist or hard-to-fill part-time roles, or where the job cannot truly be done in reduced hours without compromise. The pro rata principle is a floor, not a ceiling.
Full-time statutory entitlement is 28 days (including bank holidays). Pro rata this by your fraction of full-time hours. For 25 hours out of 37.5: 28 × (25 ÷ 37.5) = 18.67 days. Since holidays must be taken in whole days, this is typically rounded up to 19 days.
They mean the same thing — pro rata salary is the correct part-time pay based on the proportion of full-time hours worked. The term “pro rata” simply means the salary has been scaled proportionally rather than offered at a different rate. Use our Take-Home Pay Calculator to see net pay on any pro rata salary.
How to Use the Pro-Rata Salary Calculator
Enter the full-time equivalent (FTE) annual salary — this is the salary the role pays for a standard full working week, typically 37.5 or 40 hours in UK employment. Then enter your contracted part-time hours per week. The pro-rata calculation divides the FTE salary by FTE hours and multiplies by your actual hours to give your adjusted annual salary.
Pro-rata applies to all elements of pay: basic salary, most contractual allowances, and in many cases bonus entitlements. It also affects statutory entitlements — holiday entitlement, for example, is pro-rated for part-time workers but must be no less proportional than what a full-time employee receives. The legal minimum for part-time workers is the same proportion of the full-time allowance.
Note that pro-rata salary affects some other calculations. Mortgage lenders assess affordability based on your actual employed income, so your reduced salary is the figure used in affordability assessments. Similarly, statutory maternity pay is based on your average weekly earnings over a reference period — if you are planning parental leave, understanding your actual salary figure (not the FTE equivalent) matters for statutory pay calculations.
The tax and take-home results use your pro-rata salary as the input. Even if you know the FTE salary and could calculate the take-home on that, the actual figures on your payslip are based on your pro-rata income. Use the take-home result to budget accurately for your actual working arrangement rather than the FTE equivalent.
Important Information
This calculator is provided for general information and planning purposes only. It does not constitute financial or tax advice and should not be relied upon as such. Figures are indicative estimates based on simplified, publicly available criteria and stated assumptions. Actual results depend on your full circumstances. See our Disclaimer for further information.