Pro rata salary explained for part-time workers

The basic formula, briefly

Pro rata simply means 'in proportion'. A part-time role advertised against a full-time-equivalent salary pays that salary scaled down by the proportion of full-time hours or days you actually work: pro rata salary = full-time salary × (your hours or days ÷ full-time hours or days). Our Pro Rata Calculator handles this instantly — this guide goes further, into the entitlements that scale the same way, which is where most of the confusion about part-time pay actually comes from.

Holiday entitlement scales the same way — with one catch

By law, part-time workers get the same holiday entitlement as a full-time employee doing the same job, scaled to their hours. The UK statutory minimum is 5.6 weeks of paid holiday a year for a full-time worker — for someone working 3 days a week, that's 5.6 × 3 = 16.8 days, not a flat smaller number pulled from nowhere.

The catch is bank holidays. Full-time employees in the UK get 8 bank holidays a year, usually on top of their normal leave. A part-time worker whose fixed working days never fall on a bank holiday (say, someone who only works Tuesdays to Thursdays) can end up missing out on that benefit entirely unless their contract specifically gives a pro rata bank holiday entitlement — worth checking explicitly rather than assuming it's automatic.

Pro rata across different parts of a job offer

A worked example: comparing two part-time offers

Say you're deciding between two roles advertised at the same £33,000 full-time-equivalent salary. Role A is 3 days a week (0.6 of full-time): pro rata salary £19,800, pro rata statutory holiday 16.8 days. Role B is 4 days a week (0.8 of full-time): pro rata salary £26,400, pro rata statutory holiday 22.4 days. On a daily rate basis, Role A pays £19,800 ÷ (0.6 × 260 days) = £126.92 a day worked, while Role B pays £26,400 ÷ (0.8 × 260 days) = £126.92 a day worked too — identical, as you'd expect from the same full-time-equivalent figure. The real differences to weigh up are the extra day a week of actual time committed, and whether either role's fixed working days happen to capture any bank holidays.

Pro rata when you join or leave mid-year

The same scaling idea applies to someone joining or leaving a job partway through the year, not just to part-time hours. A £33,000 full-time role started exactly halfway through the tax year, on 6 October, would typically be paid roughly half of £33,000 for that tax year — scaled by the proportion of the year actually worked, in the same way a part-time role is scaled by the proportion of the week worked. This matters when comparing a payslip against an annual salary figure, since a part-year salary will naturally look lower than the full annual figure even though the pro rata rate itself hasn't changed.

Common mistakes

• Assuming part-time holiday is just 'less' rather than proportionally scaled — it should match your proportion of full-time hours exactly, not an arbitrary smaller number.
• Forgetting to check bank holiday entitlement specifically — if your contracted days never include a bank holiday, you could lose that benefit unless your contract accounts for it separately.
• Comparing two part-time offers by salary alone — the effective daily or hourly rate (and how holiday, pension and other benefits scale) often matters more than the headline pro rata salary.
• Assuming pension contributions are based on the full-time-equivalent salary — they're almost always calculated on your actual pro rata pay, so a 5% pension contribution on a 0.6 FTE role is 5% of the pro rata salary, not the full-time figure.
• Not reading how a contract defines 'full-time' hours — 35, 37.5 and 40 hours a week are all common definitions, and the one your employer uses changes your pro rata proportion even at the same number of days worked.