How to Work Out Pro Rata Salary
If you’ve ever stared at a job advert that says “£32,000 pro rata” and thought right, but what will I actually be paid? you’re in the right place. This guide walks you through how to work out pro rata salary properly, with the exact formulas, worked examples using current 2026/27 UK figures, and the bits most articles skip, like holiday, bank holidays and what lands in your bank account after tax.
It’s written for both sides of the desk: employees checking their pay is correct, and employers (or HR and payroll teams) who need to get the maths right and stay on the right side of the law. Pro rata isn’t complicated once you’ve seen it done once. It just gets dressed up to look harder than it is.
Want the number in five seconds? Use our free pro rata salary calculator and read on to understand exactly what it’s doing.
- What “pro rata” actually means
- Who gets paid pro rata (and who doesn’t)
- The pro rata salary formula
- Three worked examples with real numbers
- Pro rata pay vs take-home pay
- Pro rata holiday entitlement
- Bank holidays, sick pay and benefits
- Common mistakes to avoid
- How to check your own pay is right
- FAQs
What does “pro rata” actually mean?
Pro rata is Latin for “in proportion”. In a salary context it means you’re paid a share of a full-time wage that matches the share of full-time hours you work.
So when a job is advertised at “£30,000 pro rata”, that £30,000 is the full-time equivalent (FTE) figure — what someone would earn doing the role full-time. If you work half the hours, you get half the money. Work 60% of the hours, you get 60% of the salary. That’s the whole idea.
The phrase trips people up because the advertised number is never the number you take home if you’re part-time. It’s the reference point, not the offer.
Who gets paid pro rata (and who doesn’t)?
Pro rata pay usually applies to:
- Part-time staff — the classic case, where someone works fewer hours than the full-time standard.
- Term-time and seasonal workers — think teaching assistants or exam invigilators who work fewer than 52 weeks a year.
- Mid-month joiners and leavers — if you start or finish part way through a pay period, your first or last payslip is prorated for the days you actually worked.
- Job shares — two people splitting one full-time role.
- Anyone taking a period of unpaid leave — pay is reduced in proportion to the time off.
It generally does not apply to genuine freelancers, contractors or temps invoicing for their work, because they’re not on a salary in the first place — they’re paid for output or by the day at an agreed rate.
One legal point worth knowing: under the Part-time Workers Regulations, you cannot treat part-time staff less favourably than full-timers. Same hourly rate, same access to benefits, just scaled to their hours. Getting the pro rata sum wrong isn’t only awkward — it can become a tribunal problem.
How to work out pro rata salary: the formula
There are two ways to get to the same answer. Pick whichever matches how your contract is written.
Method 1 — the hours-based calculation
This is the one most UK employers use, and it’s the cleanest. You work out the hourly rate first, then scale it up.
You can shorten that, because the two 52s cancel out:
Both give an identical result. The long version is handy when you also want the hourly rate (useful for checking minimum wage); the short version is faster when you just need the salary.
Method 2 — the days-based calculation
If your contract is written in whole days rather than hours (say, 3 days out of 5), use days instead:
As long as your daily hours are consistent, days and hours give the same figure. A 3-day week is 60% of a 5-day week, and 22.5 hours is 60% of a 37.5-hour week — same proportion, same pay.
The 30-second percentage check
Before you trust any number, do a rough sense-check in your head. Work out what fraction of full-time hours you do, then apply it to the salary. Half the hours? Halve the salary. A quarter? Quarter it. If the figure you’ve been given is miles off that, something’s wrong.
Three worked examples with real numbers
Example 1: a standard part-time role
A marketing role pays £36,000 full-time, based on a 37.5-hour week. You’re hired for 22.5 hours a week.
- Proportion of full-time: 22.5 ÷ 37.5 = 0.6 (60%)
- Pro rata salary: £36,000 × 0.6 = £21,600 a year
Want to double-check via the hourly route? £36,000 ÷ 37.5 ÷ 52 = £18.46 an hour. Then £18.46 × 22.5 × 52 = £21,600. Same answer.
Example 2: a term-time worker (fewer than 52 weeks)
This is where a lot of online calculators quietly get it wrong, because they assume everyone works all 52 weeks. A teaching assistant has an FTE salary of £24,000, works full-time hours but only during 39 term weeks of the year.
- Proportion of the year worked: 39 ÷ 52 = 0.75
- Pro rata salary: £24,000 × 0.75 = £18,000 a year
If a term-time worker is also part-time, you apply both fractions. Say the same person works 30 hours instead of 37.5 across those 39 weeks: £24,000 × (30 ÷ 37.5) × (39 ÷ 52) = £24,000 × 0.8 × 0.75 = £14,400.
Example 3: starting or leaving mid-month
You join on a £30,000 salary, but your start date is the 16th of a 30-day month, so you only work 15 of the days.
The simplest reliable method is to work in calendar days:
- Daily rate for that month: (£30,000 ÷ 12) ÷ 30 days = £83.33
- Pay for 15 worked days: £83.33 × 15 = £1,250 gross for the first month
Some payrolls prorate by working days rather than calendar days, and some use a fixed 1/260 working-days-per-year method. They land in roughly the same place. If your first payslip looks odd, ask payroll which method they apply — there isn’t one legally mandated formula for partial months, so consistency is what matters.
Pro rata salary vs take-home pay
Here’s the thing nobody mentions until your first payslip lands: the pro rata figure you’ve just calculated is gross — before tax. What actually reaches your account is lower, because income tax, National Insurance and pension come off the prorated amount.
The good news for part-timers is that a smaller salary often means a smaller slice goes to tax. Using 2026/27 rates:
| Deduction | 2026/27 rule |
|---|---|
| Personal allowance | You pay no income tax on the first £12,570 you earn. |
| Income tax (basic rate) | 20% on earnings between £12,570 and £50,270. |
| Employee National Insurance | 8% on earnings between £12,570 and £50,270; 2% above that. |
| Workplace pension | Typically 5% employee contribution under auto-enrolment, taken from qualifying earnings. |
So in Example 1, the £21,600 pro rata salary sits above the personal allowance. You’d pay 20% tax and 8% NI on the slice above £12,570 — roughly £9,030 of taxable income — plus pension. A pro rata salary that lands below £12,570 pays no income tax at all, which is why some very part-time roles take home almost exactly their gross.
Scotland sets its own income tax bands, so if you’re a Scottish taxpayer the tax slice differs slightly. National Insurance and the personal allowance are the same UK-wide.
Don’t forget pro rata holiday entitlement
Salary is only half the calculation. Holiday gets prorated too, and this is where employers most often slip up.
Almost every UK worker is entitled to 5.6 weeks of paid holiday a year. For someone on a 5-day week that’s 28 days (which can include bank holidays). Part-timers get the same 5.6 weeks, scaled to their days:
| Days worked per week | Annual holiday entitlement |
|---|---|
| 5 days | 28 days |
| 4 days | 22.4 days |
| 3 days | 16.8 days |
| 2 days | 11.2 days |
| 1 day | 5.6 days |
What about bank holidays, sick pay and benefits?
Bank holidays
This catches people out. A part-timer who never works Mondays would lose out if bank holidays were only honoured on the days they happen to work, since most UK bank holidays fall on a Monday. To keep things fair, bank holidays are folded into the overall pro rata holiday allowance rather than granted as separate days off. The cleanest approach is to include the prorated bank holiday share inside the total entitlement figure.
Statutory Sick Pay (SSP)
SSP is not prorated the way salary is. The rate is £123.25 a week (2026/27) regardless of how many hours you work, and from April 2026 it’s paid from the first day of sickness rather than the fourth. What changes for part-timers is the number of qualifying days — a 3-day-week worker off sick for a week gets SSP for 3 qualifying days, not 5. If someone earns below the lower earnings limit, different rules apply, so check the current threshold.
Bonuses and benefits
Under the Part-time Workers Regulations, benefits scale proportionally. If a full-timer gets a £1,000 bonus, a part-timer on 50% of the hours should get £500. Health cover, training, pension access — all available on the same proportionate basis. Part-time doesn’t mean second-class.
Common pro rata mistakes (and how to avoid them)
- Treating the advertised salary as the offer. “£40,000 pro rata” for a 3-day role is £24,000, not £40,000. Always confirm the actual figure in writing.
- Forgetting term-time weeks. A full-time-hours, term-time-only role still needs the weeks-worked fraction applied. Miss it and you’ll overpay or, worse, the worker will be underpaid.
- Rounding holiday down. Tempting for a tidy number, but not allowed.
- Mixing up gross and take-home. Quote pro rata salaries gross, then calculate deductions separately.
- Ignoring minimum wage on the hourly rate. Always divide the pro rata salary back down to an hourly figure and check it clears the National Living Wage (£12.71 from April 2026). A low FTE salary spread over many hours can quietly breach it.
How to check your own pro rata salary is right
If you suspect your payslip is off, here’s a five-minute audit:
- Find the FTE salary for your role — it’s usually in your contract or the original job advert.
- Work out your fraction of full-time hours (your weekly hours ÷ the full-time standard).
- Multiply the FTE salary by that fraction. That’s your gross pro rata salary.
- Divide by 12 for your gross monthly pay, then compare with your payslip’s gross figure (before deductions, not the net).
- If it doesn’t match, check whether term-time weeks, a different full-time hours figure, or a salary-sacrifice arrangement explains the gap before you raise it.
If the numbers still don’t line up after that, it’s a fair question for payroll or HR. Most discrepancies come down to a different assumption about full-time hours, not deliberate error.
Frequently asked questions
What does £30,000 pro rata mean for part-time work?
It means £30,000 is the full-time salary for the role. Your actual pay is a proportion of that based on your hours. Work 50% of full-time hours and you’d earn £15,000; work 60% and you’d earn £18,000.
How do I work out pro rata salary from an annual figure?
Multiply the full-time annual salary by your hours divided by full-time hours. For example, £28,000 × (24 ÷ 37.5) = £17,920. If you work fewer than 52 weeks a year, also multiply by your weeks divided by 52.
Is pro rata salary calculated before or after tax?
Before tax. Pro rata is always worked out on gross pay. Income tax, National Insurance and pension are then deducted from the lower prorated figure, the same way they would be from any salary.
Do part-time workers get the same hourly rate as full-time staff?
Yes. By law, part-time staff must receive the same hourly rate as a full-time colleague doing the same job. Pro rata only reduces the total because of fewer hours — never the rate per hour.
How is pro rata holiday entitlement calculated?
Multiply the days you work each week by 5.6. So a 3-day-a-week worker gets 16.8 days of paid holiday a year. The result can’t be rounded down.
Does pro rata apply to mid-month starters?
Yes. If you start or leave part way through a pay period, that payslip is prorated for the days you actually worked, usually by calendar days or working days depending on your employer’s payroll method.
Is Statutory Sick Pay reduced for part-time workers?
No. SSP is a flat weekly rate (£123.25 for 2026/27) and isn’t scaled down by hours. What changes is the number of qualifying days it’s paid across, based on the days you normally work.
The bottom line
Once you’ve seen it laid out, working out a pro rata salary comes down to one honest question: what fraction of full-time am I actually doing? Apply that fraction to the full-time salary and you’ve got your gross pay. Apply the same logic to holiday, bonuses and benefits and you’ve covered nearly everything. Knowing how to work out pro rata salary protects employees from quiet underpayment and keeps employers clear of avoidable disputes.
The maths is genuinely simple — it’s the term-time weeks, the mid-month days and the holiday rounding that catch people out. If you’d rather skip the arithmetic, run your figures through our pro rata salary calculator and check the result against the worked examples above.
This guide is general information, not financial or legal advice. For specific payroll or contractual queries, check the current figures on GOV.UK or speak to a qualified accountant or HR adviser.
