Pro Rata Salary Calculator UK — Part-Time & Holiday Pay

Pro rata is Latin for "in proportion". In employment, it means your pay and benefits are calculated as a proportion of the full-time equivalent. If a full-time salary is £30,000 for 37.5 hours per week and you work 22.5 hours, your pro rata salary is £18,000 — 60% of the full-time rate.

Pro rata salary = Full-time salary × (Your hours per week ÷ Full-time hours per week). Example: £30,000 full-time salary at 37.5 hours per week, working 25 hours = £30,000 × (25 ÷ 37.5) = £20,000 pro rata annual salary.

Pro rata holiday = Full-time holiday entitlement × (Your days per week ÷ Full-time days per week). Example: 28 days full-time entitlement, working 3 days out of 5 = 28 × (3 ÷ 5) = 16.8 days pro rata holiday. The UK statutory minimum holiday entitlement for part-time workers is 5.6 weeks per year.

UK part-time workers are entitled to the same holiday as full-time workers on a pro rata basis. The full-time minimum is 28 days (5.6 weeks, including bank holidays). A part-time worker on 3 days per week is entitled to at least 16.8 days (28 × 3/5). Employers cannot give part-time workers less holiday than full-time workers on a pro rata basis — it is illegal under the Part-time Workers Regulations 2000.

Your pro rata salary is the gross salary before any deductions. Pension contributions, tax, and National Insurance are all calculated on your pro rata gross pay — not on the full-time salary. Auto-enrolment applies if you earn above £10,000 per year. If your pro rata salary is below this threshold, you may need to opt in to your workplace pension manually.

For a £35,000 full-time job on a standard 5-day week, working 3 days gives a pro rata salary of £35,000 × (3 ÷ 5) = £21,000 per year. Monthly take-home (after basic rate income tax and NI) would be approximately £1,500–£1,600. Use this calculator to model different hour combinations and see monthly and weekly pay instantly.

Yes. If you receive a salary increase partway through the year, the pro rata calculation shows how much you will earn for the remaining months. Enter the new full-time salary, use 12 as full-time hours and the remaining months as your hours — this gives the pro rata amount for the partial year. Alternatively, speak to payroll who will apply the new rate from the effective date.