Pro-rata salary calculator
Working 22.5 hours per week against a 37.5-hour full-time week is 60.0% of full time. On a £35,000 full-time salary that is £21,000.00 pro rata — £18,639.60 after tax.
2026/27 rates. Assumes a standard tax code, no pension and no student loan — add those in the full calculator.
Pro-rata take-home pay
£18,639.60
60.0% of the full-time salary
Full-time vs pro rata
Full time — gross
£35,000.00
£28,719.60 take-home
Pro rata — gross
£21,000.00
£18,639.60 take-home
You keep 64.9% of the full-time take-home for 60.0% of the hours, because the personal allowance is a fixed amount rather than a proportion of pay.
How pro-rata pay works
Pro rata simply means “in proportion”. Your salary is the full-time figure scaled by the share of full-time hours you actually work, so the hourly rate stays the same. The full-time equivalent is whatever the employer treats as a full week — commonly 37.5 or 40 hours, or five days.
Tax is where it gets more interesting. The personal allowance is a flat £12,570, not a proportion of pay, so it covers a larger share of a part-time salary. That is why the take-home percentage above is higher than the hours percentage.
Pro-rata pay questions
Sources & last updated
- GOV.UK — Part-time workers: your rights
- GOV.UK — Income Tax rates and Personal Allowances
- HMRC — Rates and thresholds for employers 2026 to 2027
Rates checked against the sources above and last reviewed for the 2026/27 tax year. This is a guidance tool, not tax or legal advice — for anything that turns on your own circumstances, speak to a qualified adviser. See how we calculate for the full method.