Pro-Rata Salary Calculator
Job adverts quote the full-time salary. Enter it with your actual hours to see what you will really be paid.
Pro-rata take-home pay
£1,553 a month
| Full time | Your hours | |
|---|---|---|
| Gross salary | £35,000 | £21,000 |
| Income Tax | £4,486 | £1,686 |
| National Insurance | £1,794 | £674 |
| Take-home | £28,720 | £18,640 |
- Take-home per month
- £1,553
- Take-home per week
- £358
- Effective tax rate
- 11.2%
- Marginal rate
- 28%
How pro-rata pay works
Pro rata simply means "in proportion". If a role is advertised at £35,000 for a 37.5-hour week and you work 22.5 hours, you are working 60% of full time, so your salary is 60% of £35,000 — £21,000. Tax is then worked out on the £21,000, not on the full-time figure.
This matters more than it looks, because the personal allowance is a fixed amount rather than a proportion. A part-timer keeps a larger share of their pay than a full-timer on the same role, since more of it falls inside the tax-free allowance.
What pro rata does and does not cover
Holiday entitlement is pro-rated too: the statutory minimum is 5.6 weeks of your working week. Bank holidays are usually pro-rated as well, which can leave part-timers who never work Mondays slightly worse off unless the employer converts the entitlement into hours.
Pension contributions are normally a percentage, so they scale automatically. But auto-enrolment has an earnings trigger — if your pro-rata salary falls below it, your employer does not have to enrol you automatically, though you can still ask to join.
Common questions
How do I calculate pro-rata salary?
Divide your hours by the full-time hours, then multiply by the full-time salary. For 22.5 hours against a 37.5-hour week that is 0.6, so a £35,000 role pays £21,000.
Do part-time workers pay less tax proportionally?
Yes. Because the £12,570 personal allowance is a flat amount rather than a percentage, it covers a bigger share of a smaller salary. A part-timer on £21,000 pays a lower effective rate than a full-timer on £35,000.
Is pro-rata holiday calculated the same way?
It follows the same proportion. The statutory minimum is 5.6 weeks of your normal working week, so someone working three days a week is entitled to 16.8 days rather than 28.