Free UK employment calculator

Pro-rata salary calculator for part-time staff

Turn a full-time salary into part-time pay, work out pay for someone joining or leaving mid-month, and check the hourly rate against the National Minimum Wage rates from 1 April 2026.

Figures checked 15 October 2026 · England, Wales and Scotland

Calculator

Where does the employee work?

Full-time salary (£ a year)

Full-time hours a week

Part-time hours a week

Employee's age, for the minimum wage check

Joining or leaving mid-month?

Uses the pro-rata salary above, or the full-time salary if you have not entered part-time hours.

First day paid this month

Last day paid this month

What does the contract or pay policy say about part months?

How it is worked out

Part-time workers must be paid at least the same rate as a comparable full-time worker, for the proportion of hours they work. This is the "pro rata principle" in the Part-time Workers Regulations 2000 (reg 1(2) and reg 5).

Pro-rata salary = full-time salary × part-time hours ÷ full-time hours. Monthly pay is the annual figure divided by 12, and weekly pay is the annual figure divided by 52.

For a part month, use the method the contract or an incorporated pay policy sets out. Where it says nothing, salary is treated as building up day by day (Apportionment Act 1870, s2), so each calendar day is worth 1/365 of the annual salary, or 1/366 in a leap year (Hartley v King Edward VI College [2017] UKSC 39).

The hourly figure is checked against the minimum wage rates from 1 April 2026. It is a guide only: minimum wage law has its own rules for working out a salaried worker's hours.

Worked example

A full-time role pays £30,000 for 37.5 hours a week. Alex works 22.5 hours, which is 60%, so their salary is £18,000, or £1,500 a month. That is £15.38 an hour, comfortably above the £12.71 National Living Wage.

Questions employers ask

+How do you calculate a pro-rata salary?

Divide the part-time weekly hours by the full-time weekly hours and multiply the full-time salary by the result. 22.5 hours against a 37.5-hour week on £30,000 gives £18,000.

+Do part-time workers have a legal right to pro-rata pay?

Part-time workers must not be treated less favourably than comparable full-time workers, and the pro rata principle applies unless it is inappropriate (Part-time Workers Regulations 2000, reg 5). In practice that means at least the full-time rate for the proportion of hours worked, plus pro-rata benefits and holiday.

+How do I pay someone for part of a month?

Follow the method in the contract or an incorporated pay policy, whether that is calendar days or working days in the month. If the contract says nothing, salary is treated as building up day by day, so each calendar day is worth 1/365 of the annual salary, or 1/366 in a leap year (Apportionment Act 1870, s2; Hartley v King Edward VI College [2017] UKSC 39).

+What is the National Living Wage from April 2026?

£12.71 an hour for workers aged 21 and over, £10.85 for 18 to 20, and £8.00 for under-18s and apprentices, from 1 April 2026.

+Does a salaried part-timer get paid overtime at the full rate?

Not necessarily. A lower overtime rate can lawfully apply until the part-timer's hours go above the full-time hours of a comparable worker (reg 5(4)).

Sources

This calculator gives a general estimate based on the law and statutory figures in force on 15 October 2026 for England, Wales and Scotland. It is not legal advice and does not take account of your contract, your policies or any special circumstances. Contractual terms can give more than the statutory minimum, never less. Northern Ireland has its own rules and limits and is not covered. Nothing you enter is stored or sent anywhere: the sums are done in your browser.