Free pro rata calculator
Choose what you want to work out. Results are gross (before tax, National Insurance and pension).
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Pro Rata Calculator: Work Out Part-Time Salary, Part-Year Pay and Holiday
This pro rata calculator turns a full-time salary or holiday allowance into the proportion that actually applies to you. It is built for part-time workers, people starting or leaving a job mid-year, and anyone checking a contract offer before they sign.
Quick answer: pro rata pay = full-time salary × (your hours ÷ full-time hours). A £36,000 job at 37.5 hours a week pays £23,040 if you work 24 hours. Use the calculator below for your own numbers, then read the sections after it to see which method your employer should be using.
What the calculator assumes
- Part-time salary: your pay scales in direct proportion to hours (or days). Hourly rate is the full-time salary divided by full-time hours × 52.
- Part-year pay: your annual salary is spread evenly across the year. Calendar-day mode divides by 365 (366 when both dates fall in the same leap year).
- Holiday: statutory leave is 5.6 times your working week, capped at 28 days. The contract figure uses your employer’s own full-time allowance. Rounding follows the GOV.UK calculator, which rounds up to the nearest half day.
- Not included: tax, National Insurance, pension contributions, overtime, bonuses, unpaid leave, or sick pay.
What does pro rata mean?
Pro rata is Latin for “in proportion”. In employment it means you receive a share of something (pay, holiday, a bonus, a benefit) that matches the share of a full-time job you actually do. Work three days in a five-day role and you get three-fifths of the full-time figure.
You will see the phrase in three everyday situations: a salary advertised as “£30,000 pro rata” (the figure is for full-time, and you will be paid less if you work fewer hours), a holiday allowance quoted “pro rata”, and a first or last pay packet when you join or leave part-way through a year. If a job advert says “£12,000 pro rata”, that is not a low salary. It is the actual take-home for the hours you will work, expressed on a full-time basis.
That last point catches people out. A pro rata figure in an advert tells you the full-time equivalent (FTE) rate. Your real pay is that number multiplied by your fraction of full time.
How to calculate pro rata salary
There are two standard methods. Both give the same answer when your full-time week is stable, so pick the one that matches how your contract is written.
Worked example: hours method
A role pays £36,000 for a 37.5-hour week. You have been offered 24 hours.
- Work out your fraction: 24 ÷ 37.5 = 0.64 (64% of full time).
- Multiply: £36,000 × 0.64 = £23,040 a year.
- Monthly: £23,040 ÷ 12 = £1,920. Weekly: £23,040 ÷ 52 = about £443.08.
- Hourly check: £36,000 ÷ (37.5 × 52) = about £18.46, and £18.46 × 24 × 52 lands on the same annual figure.
Worked example: days method
A £30,000 full-time salary, five days a week. You work three days: £30,000 × 3 ÷ 5 = £18,000.
Reference table: fraction of full time
| Days per week | Fraction of full time | Pay on a £30,000 FTE salary |
|---|---|---|
| 1 | 20% | £6,000 |
| 2 | 40% | £12,000 |
| 3 | 60% | £18,000 |
| 4 | 80% | £24,000 |
| 5 | 100% | £30,000 |
Which method should you use?
Use hours when your days are different lengths (say 6 hours on Monday and 9 on Thursday). Use days when every working day is the same length. If your employer’s full-time week is unusual, such as 35 or 40 hours, use their figure, not the national average. Ask HR or your manager which full-time number the contract is based on, because a mismatch of even 2.5 hours changes your pay by several percent.
Turning a pro rata salary into take-home pay
Everything above is gross. Income tax, National Insurance and any pension deduction come off afterwards, and they do not scale in a straight line, because tax bands and allowances are fixed amounts. Someone at 60% of a £30,000 job will not take home exactly 60% of the full-time net figure, since more of their income falls inside the tax-free allowance. Use a net pay tool such as our UK take-home pay calculator for that step rather than multiplying net pay by the same fraction. To see how the tax bands apply to your pro rata figure, try the UK income tax calculator, and if you repay a plan loan, the UK student loan calculator shows that deduction too.
Starting or leaving part-way through the year
Pro rata also applies to time. If you start on 15 July and the pay year ends on 31 December, you are paid for the days you are employed, not the whole year.
Worked example: annual salary £42,000, first day worked 15 July, employed to 31 December. That is 170 calendar days (17 in July, then 31, 30, 31, 30 and 31). £42,000 × 170 ÷ 365 = £19,561.64 gross for the period.
Some payrolls use working days or monthly twelfths instead of calendar days. Monthly twelfths is simple (salary ÷ 12 per full month) but gets fiddly for part months, which is why many employers count days. Neither method is wrong; what matters is that your contract or payroll policy says which is used. The two can differ by a few pounds on a single pay slip, and that is worth knowing before you query it.
Pro rata holiday entitlement
Part-time workers in the UK get the same statutory holiday as full-time colleagues, in proportion. The legal minimum is 5.6 weeks a year. For someone working five days a week that is 28 days, and for everyone else it is 5.6 times their working week. This is set out on GOV.UK’s holiday entitlement page, and the official GOV.UK holiday calculator covers other working patterns. For a quick UK check, you can also use our UK holiday entitlement calculator or the annual leave calculator.
| Days worked per week | Statutory days (exact) | Rounded up to half day |
|---|---|---|
| 1 | 5.6 | 6 |
| 2 | 11.2 | 11.5 |
| 3 | 16.8 | 17 |
| 4 | 22.4 | 22.5 |
| 5 | 28 | 28 |
Contractual holiday and bank holidays
Many employers give more than the legal minimum, such as 25 days plus 8 bank holidays. In that case the pro rata rule applies to the whole package. Take a full-time contract with 33 days in total (25 plus 8 bank holidays). A colleague working three days a week gets 33 × 3 ÷ 5 = 19.8 days, which rounds to 20. The holiday tab handles this with the “full-time contract allowance” field.
Bank holidays are where part-timers most often lose out. If you never work Mondays, you miss more bank holidays than someone who works Tuesday to Friday. Being paid the same daily rate for a smaller pool of days would leave you worse off, which is why the whole allowance is pro-rated and you then book leave from it. Your contract should say whether bank holidays are inside or on top of the total.
Joining or leaving mid-year
Holiday builds up from your first day. If you work part of the leave year, your entitlement is scaled by the time worked. A common approach is months worked ÷ 12, though some employers count days. The calculator’s months field does the first version. Irregular-hours and part-year workers have a specific method on GOV.UK, so check the official tool if that is you.
Working in hours
If your shifts vary, holiday is usually tracked in hours. Multiply weekly hours by 5.6: 20 hours a week gives 112 hours of leave. This avoids arguments about whether a 4-hour day and a 10-hour day should each cost “one day”.
Common mistakes when working out pro rata
- Using the wrong full-time week. Dividing by 40 when the employer’s full-time job is 37.5 understates your pay by about 6%.
- Multiplying net pay. Pro rata applies to gross salary. Take-home pay follows tax rules, not a straight fraction.
- Treating “pro rata” in an advert as your pay. It is the FTE figure.
- Rounding holiday down. The GOV.UK calculator rounds up to the nearest half day. Rounding down can leave you short.
- Forgetting bank holidays. Check whether your full-time allowance includes them before you scale it.
- Mixing methods. Working out the year in days but paying the month in twelfths can produce small mismatches. Ask which method payroll uses.
- Ignoring compressed hours. Four long days for a full-time 37.5 hours is not part-time. You are full time with a different pattern, and holiday should be worked out accordingly.
When a simple pro rata sum is not enough
The formulas here suit stable, contracted hours. They are only a starting point if any of these apply:
- Zero-hours or highly variable shifts. Pay follows the hours worked; holiday may accrue as a percentage of hours. Extra hours paid at a higher rate can be checked with an overtime calculator for the UK.
- Shared or unequal benefits. Pensions, bonuses and car allowances can follow their own rules, and the company handbook decides.
- Mid-year contract changes. Going from full to part-time part-way through the year means calculating each period separately and adding them together.
- Different countries. Holiday rules, rounding and statutory minimums vary. This page uses UK figures for holiday; salary maths works anywhere.
- Disputes. If a payslip looks wrong, the calculator gives you a sanity check, not a legal ruling. Raise it with payroll first, and use Acas for free impartial guidance if it is not resolved.
UK part-time workers also have a right not to be treated less favourably than comparable full-time colleagues, unless the difference is objectively justified. The rule comes from the Part-time Workers (Prevention of Less Favourable Treatment) Regulations 2000, and GOV.UK’s part-time worker rights page summarises it in plain English.
Frequently asked questions
What is pro rata?
It means “in proportion”. A pro rata figure is a share of a full-time amount that matches the share of full-time work you do or the fraction of the year you are employed.
How do you work out a pro rata salary?
Divide your hours by full-time hours, then multiply by the full-time salary. For 24 hours against a 37.5-hour week on £36,000, that is £36,000 × 0.64 = £23,040.
How do you calculate pro rata payments for part of a year?
Divide the days you are employed by the days in the year and multiply by the annual salary. Check whether payroll counts calendar days, working days or monthly twelfths.
What does pro rata mean in wages?
It means pay proportional to hours worked. A “£30,000 pro rata” job pays £30,000 to a full-time employee and less to someone working reduced hours.
How much holiday do part-time workers get in the UK?
The statutory minimum is 5.6 times the working week, so 16.8 days for a three-day week and 22.4 for four days. Employers may offer more.
Do bank holidays count towards pro rata holiday?
They can be included in the 5.6-week minimum, but only if your contract says so. If they are extra, the total package is pro-rated.
Is the pro rata calculator accurate?
The arithmetic is exact for the inputs you give. Real payslips can differ because of tax codes, pension schemes, rounding policy and how your employer counts days.
Bottom line
Pro rata maths is simple once you know which two numbers matter: your share of full time, and the amount that share applies to. Run the calculator with the exact full-time week in your contract, confirm whether bank holidays sit inside the allowance, and ask payroll how part months are counted. Those three checks catch most errors before they cost you money. For more tools, browse our UK financial calculators hub.
Sources and further reading
- GOV.UK: Holiday entitlement – statutory 5.6 weeks and part-time rules
- GOV.UK: Calculate holiday entitlement – official calculator, including irregular hours
- GOV.UK: Part-time worker rights – equal treatment
- legislation.gov.uk: Part-time Workers Regulations 2000