To calculate salary pro rata, divide the full-time equivalent (FTE) annual salary by the total full-time weekly hours to get an hourly rate, then multiply by your contracted part-time hours. This gives you a proportionate annual salary that reflects the hours you actually work. The pro rata salary calculation formula applies equally whether you’re moving to part-time, starting a new role, or checking a job offer against what you’d expect to earn.
The Pro Rata Salary Calculation Formula
The core formula is straightforward:
Pro Rata Salary = (Full-Time Salary ÷ Full-Time Hours) × Your Contracted Hours
Everything else — monthly breakdowns, day-rate variations, term-time contracts — is just a version of this same logic applied to different working patterns.
If your employer works in days rather than hours, the formula adjusts slightly:
Pro Rata Salary = Full-Time Salary × (Your Contracted Days ÷ Full-Time Days)
Both produce the same result as long as your daily hours are consistent throughout the week.
How to Calculate Pro Rata Salary: Step by Step
Step 1 — Find the Full-Time Equivalent Salary
The FTE salary is the annual pay for the role if it were worked full-time. You’ll find this in your contract, the job advertisement, or by asking HR directly. Always use the contractual FTE figure — not a rough industry average.
Step 2 — Establish the Full-Time Weekly Hours
This is the number of hours a full-time employee works at your company. Common figures are 37.5 hours or 40 hours per week. Use the correct contractual hours for the role — not a rounded number — because even a small difference changes the outcome meaningfully at higher salaries.
Step 3 — Divide to Get Your Hourly Rate
Divide the FTE salary by the full-time weekly hours:
Hourly Rate = FTE Salary ÷ Full-Time Weekly Hours
For example, a £35,000 FTE salary on a 37.5-hour week gives an hourly rate of £933.33 (annual) — or more practically: £35,000 ÷ 37.5 = £933.33 per weekly hour worked.
Step 4 — Multiply by Your Contracted Hours
Multiply that hourly rate by your actual part-time contracted hours:
Pro Rata Salary = Hourly Rate × Your Contracted Hours
Worked Example: Calculating Pro Rata Pay
Scenario: A role is advertised at £42,000 FTE. Full-time hours are 37.5 per week. You’ll be working 28 hours per week.
- Hourly rate: £42,000 ÷ 37.5 = £1,120 per hour (annual equivalent)
- Pro rata salary: £1,120 × 28 = £31,360 per year
Monthly, that’s £31,360 ÷ 12 = £2,613.33 gross per month.
You can verify this quickly using the ratio method: 28 ÷ 37.5 = 74.67%, so £42,000 × 0.7467 = £31,361. Both approaches land in the same place.
Pro Rata Salary by Days Worked
Some employers — particularly in education, professional services, and public sector roles — negotiate contracts in days rather than hours. The day-rate formula works identically to the hours method:
Pro Rata Salary = FTE Salary × (Days Worked Per Week ÷ Full-Time Days Per Week)
Example: £38,000 FTE, standard week is 5 days, you work 4 days.
£38,000 × (4 ÷ 5) = £30,400 per year
If you work 3 days: £38,000 × (3 ÷ 5) = £22,800 per year
Pro Rata Salary Quick Reference Table
Common FTE-to-part-time conversions at typical UK salary points:
| FTE Salary | 4 days/week (80%) | 3 days/week (60%) | Half-time (50%) | 22.5hrs / 37.5hr week (60%) |
| £20,000 | £16,000 | £12,000 | £10,000 | £12,000 |
| £25,000 | £20,000 | £15,000 | £12,500 | £15,000 |
| £30,000 | £24,000 | £18,000 | £15,000 | £18,000 |
| £35,000 | £28,000 | £21,000 | £17,500 | £21,000 |
| £40,000 | £32,000 | £24,000 | £20,000 | £24,000 |
| £50,000 | £40,000 | £30,000 | £25,000 | £30,000 |
| £60,000 | £48,000 | £36,000 | £30,000 | £36,000 |
For any working pattern not shown here, the Pro Rata Calculator handles the arithmetic instantly — including monthly and weekly breakdowns.
How to Calculate Pro Rata Monthly Salary
Once you have your annual pro rata figure, divide by 12:
Monthly Pro Rata Salary = Annual Pro Rata Salary ÷ 12
Using the earlier example of £31,360 per year: £31,360 ÷ 12 = £2,613.33 per month gross.
Bear in mind your take-home pay will be lower once Income Tax, National Insurance, and any pension contributions are deducted. For 2026/27, the personal allowance remains £12,570, and the basic rate of Income Tax (20%) applies to earnings between £12,571 and £50,270, as confirmed by HMRC’s current tax year guidance.
How to Calculate Pro Rata Salary in Excel
If you prefer to build your own calculation rather than use an online tool, Excel makes this straightforward.
Set up three cells:
- Cell A1: FTE Salary (e.g. 42000)
- Cell A2: Full-Time Weekly Hours (e.g. 37.5)
- Cell A3: Your Contracted Hours (e.g. 28)
In Cell A4, enter the formula:
=A1/A2*A3
This returns your annual pro rata salary. For monthly pay, add:
=A4/12
For a quick proportional check, add:
=A3/A2 — this tells you your hours ratio (e.g. 0.7467, or 74.67% of full-time).
You can extend this to include a take-home estimate by factoring in the 2026/27 personal allowance and basic rate tax band, though payroll software or a dedicated calculator will always be more precise for net pay.
Pro Rata for Term-Time and Part-Year Workers
Workers on term-time or seasonal contracts — teaching assistants, school support staff, and similar roles — work fewer than 52 weeks per year. Their pro rata salary calculation accounts for both reduced weekly hours and a shorter annual working year:
Pro Rata Salary = FTE Salary × (Your Hours ÷ FTE Hours) × (Your Working Weeks ÷ 52)
Example: A teaching assistant earns £28,000 FTE. They work 37.5 hours per week for 39 weeks of the year.
£28,000 × (37.5 ÷ 37.5) × (39 ÷ 52) = £28,000 × 1 × 0.75 = £21,000
If the same role were part-time — say 30 hours per week for 39 weeks:
£28,000 × (30 ÷ 37.5) × (39 ÷ 52) = £28,000 × 0.8 × 0.75 = £16,800
According to guidance from Acas, term-time workers are still employees entitled to SSP, statutory maternity pay, and pension contributions — the pro rata calculation affects salary only, not employment status.
Pro Rata Holiday Pay: How It Works
Part-time workers in the UK are legally entitled to the same proportion of statutory annual leave as full-time colleagues. The statutory minimum is 5.6 weeks per year (28 days for a 5-day week), as established under the Working Time Regulations 1998.
The holiday entitlement formula for part-time workers:
Pro Rata Holiday = Days Worked Per Week × 5.6
| Working Days Per Week | Annual Leave Entitlement | Of Which: Bank Holidays (of 8) | Remaining Flexible Leave |
| 5 (full-time) | 28 days | 8.0 days | 20 days |
| 4 days | 22.4 days | 6.4 days | 16 days |
| 3 days | 16.8 days | 4.8 days | 12 days |
| 2.5 days | 14.0 days | 4.0 days | 10 days |
| 2 days | 11.2 days | 3.2 days | 8 days |
One area where employers frequently make mistakes: bank holidays for part-time workers cannot simply be the bank holidays that fall on their working days. If someone works Tuesday to Thursday and all 8 UK bank holidays fall on Mondays, they still have a statutory entitlement to their pro-rata share — equivalent time must be given on a working day or paid in lieu.
The cleanest approach is to include bank holiday entitlement within the total leave allowance. A 4-day week employee gets 22.4 days total, which absorbs their 6.4 days of pro-rata bank holiday entitlement cleanly.
Is Your Pro Rata Salary Actually Correct?
If your current salary feels wrong, here’s how to verify it in under two minutes:
- Find the FTE salary for your role — check your original contract or the job posting
- Divide your contracted hours by the full-time hours: e.g. 22.5 ÷ 37.5 = 0.60
- Multiply the FTE salary by that ratio: e.g. £35,000 × 0.60 = £21,000
- Compare to what you’re actually being paid
Under the Part-Time Workers (Prevention of Less Favourable Treatment) Regulations 2000, part-time employees have the legal right to the same hourly rate as a comparable full-time worker doing the same role. Being paid less per hour for identical work is unlawful — not just unfair.
If there’s a discrepancy, raise it with HR first. If you get nowhere, Acas provides free, confidential guidance for employees on pay disputes.
Common Mistakes Employers Make With Pro Rata Pay
These errors appear repeatedly — knowing them helps both employers and employees spot problems early.
Using the wrong FTE hours. Always use the contractual full-time hours for the specific role (typically 37.5), not a rounded figure like 40. The difference on a £40,000 salary: 37.5 vs 40 hours produces £800 per year discrepancy at 30 contracted hours.
Failing to pro-rate bank holidays properly. Giving part-timers only the bank holidays that fall on their working days is non-compliant. Entitlement is calculated proportionally from the 8 standard UK bank holidays, regardless of which days a person works.
Not recalculating when hours change. Any change in contracted hours requires an immediate recalculation of both salary and holiday entitlement from the effective date of change.
Breaching National Minimum Wage. For 2026/27, the National Living Wage is £12.71 per hour for workers aged 21 and over, and £10.85 for those aged 18–20. Always verify the implied hourly rate of any pro rata salary clears the relevant NMW floor.
Misclassifying term-time workers. Term-time contracts are employment contracts. Treating them as self-employment or freelance arrangements to avoid SSP, SMP, or pension obligations is a legal exposure, not a grey area.
What Pro Rata Salary Doesn’t Automatically Include
A pro rata salary scales your base pay. Other elements of your package may or may not be scaled proportionally — and this is where reading the contract closely matters.
Pension contributions: Most auto-enrolment schemes calculate contributions as a percentage of qualifying earnings, so contributions scale naturally with a lower salary. However, some employer contribution schemes have fixed minimums — check your scheme rules.
Bonuses: Unless your contract explicitly states bonuses are paid pro rata, a discretionary bonus may not be scaled. Ask HR to confirm in writing.
Benefits: Healthcare, life assurance, and other benefits may be offered in full regardless of hours (common in senior roles), or may be excluded entirely for part-time staff below a threshold. This should be spelled out in your contract.
Sick pay: Statutory Sick Pay (SSP) for 2026/27 is £123.25 per week — it is not reduced pro rata for part-timers. However, it is paid only for qualifying days (the days the employee normally works), so a 3-day week worker off sick for a full week receives SSP for 3 days, not 5.
Pro Rata vs Hourly Pay: What’s the Difference?
A pro rata salary is still a salary — you receive a fixed monthly amount regardless of how many exact hours you work in a given week. It is not the same as hourly pay, where your earnings fluctuate with hours worked.
The distinction matters practically: a pro rata employee on £21,000 per year (3 days/week) receives £1,750 per month every month, whether that month has 13 working days or 9 due to bank holidays. An hourly worker’s pay varies with actual hours. Pro rata employment comes with the same employment rights and stability as full-time salaried work.
Independent contractors and freelancers do not qualify for pro rata salary — they are not employees and are typically paid by project, day rate, or time logged.
Using a Pro Rata Salary Calculator
The manual formula is always reliable, but when you’re evaluating a job offer, comparing options, or working out payroll for multiple staff members, an online calculator removes room for arithmetic error.
A good pro rata salary calculator — like the one at proratacalculator— should handle hours-based and days-based inputs, produce annual, monthly, and weekly figures, and ideally show the implied take-home after tax for the current tax year. The complete UK guide to pro rata salary for 2026/27 covers more complex scenarios including part-year workers and term-time contracts.
For a broader look at how pro rata pay interacts with UK employment law, the guide to working out pro rata pay is worth reading alongside this piece.
Frequently Asked Questions
What is the formula for pro rata salary?
The standard formula is: Pro Rata Salary = (Full-Time Salary ÷ Full-Time Hours) × Your Contracted Hours. For day-based contracts: Pro Rata Salary = Full-Time Salary × (Your Days ÷ Full-Time Days). Both produce the same result when daily hours are consistent. The key is always using the correct contractual FTE hours rather than an assumed standard.
How do I calculate my salary pro rata?
Take the advertised full-time salary, divide by the full-time weekly hours to get an hourly equivalent, then multiply by your actual contracted hours. For example, £36,000 FTE on a 37.5-hour week works out to £960 per hour annually. If you work 30 hours, your pro rata salary is £960 × 30 = £28,800. Divide by 12 for your monthly gross figure.
How do I use a pro rata salary calculator?
Enter the full-time annual salary, the standard full-time weekly hours for the role, and your contracted part-time hours. A reliable calculator returns your annual, monthly, and weekly pro rata salary instantly. Some also show an estimated take-home after tax and NI for the current UK tax year, which is useful when comparing a part-time offer against your current take-home.
How do I work out my pro rata pay from my contract?
Find the FTE salary stated in your contract or original job offer. Then apply the ratio: divide your contracted hours by the full-time hours. Multiply the FTE salary by that ratio. If the result doesn’t match your actual salary, raise it with HR — the Part-Time Workers Regulations 2000 give you the right to comparable hourly pay.
What is the pro rata formula for days worked?
Pro Rata Salary = Full-Time Salary × (Your Working Days ÷ Full-Time Working Days). If the FTE salary is £45,000 for a 5-day week and you work 3 days, that’s £45,000 × (3 ÷ 5) = £27,000 per year. This is the most common approach for roles where the contract specifies days per week rather than hours.
How do you calculate pro rata salary in Excel?
Set up cells for FTE salary, full-time hours, and your contracted hours. In a fourth cell, enter =A1/A2*A3 (replacing A1, A2, A3 with your actual cell references). This returns the annual pro rata salary. Add =A4/12 for monthly pay. The formula is identical to the manual calculation — Excel just eliminates rounding errors and makes it reusable.
What is a prorated salary?
A prorated salary is an adjusted salary that reflects only the portion of time actually worked. It applies not just to part-time working patterns, but also to mid-month start dates, mid-year salary changes, or partial contract periods. In the UK, “pro rata” and “prorated” are used interchangeably — both mean the salary has been scaled proportionally to hours, days, or weeks worked.
What is the pro rata rule in employment?
In UK employment law, the pro rata principle means part-time workers must receive the same pay, benefits, and leave entitlements as comparable full-time workers — but on a proportional basis. This is enshrined in the Part-Time Workers (Prevention of Less Favourable Treatment) Regulations 2000. Paying a part-time employee a lower hourly rate than their full-time equivalent doing the same role is unlawful under these regulations.
What does pro rata mean in basic terms?
Pro rata is Latin for “in proportion.” In salary terms, it means your pay reflects the proportion of full-time hours you actually work. If you work half the standard hours, you receive half the salary. It ensures part-time workers are paid fairly relative to full-time colleagues in the same role, rather than being paid at an arbitrary reduced rate.
How does pro rata salary affect holiday entitlement?
Holiday entitlement is also calculated pro rata for part-time workers. The statutory minimum is 5.6 weeks per year (28 days for a 5-day week). A 3-day week worker is entitled to 3 × 5.6 = 16.8 days per year. Bank holidays are included within this pro-rata share — not added on top — unless your contract states otherwise.