If you know how many hours a week you’ll work, a part time hours pro rata calculator turns that single number into a full pay picture — annual salary, monthly take-home estimate, and the hourly rate behind it all. This guide gives you ready-made lookup tables for the most common part-time patterns (16 to 30 hours a week) against a £30,000 full-time salary, plus the method to adapt them to any salary. Whether you’re comparing job offers or checking your payslip, you’ll find your number here.
Why Hours Are the Key Input
Every pro rata calculation boils down to one fraction: your hours ÷ full-time hours. That fraction is applied to the full-time salary, and everything else — monthly pay, weekly pay, holiday entitlement — flows from it. Get the hours right and the rest follows.
In the UK, full-time is most commonly 37.5 hours a week, though 37 and 40 are also used. The tables below use 37.5 as the baseline, since it covers the majority of office, NHS and public-sector roles. If your employer’s full-time week is different, the method section further down shows you how to recalculate in seconds.
The Master Table: £30,000 FTE at 37.5 Full-Time Hours
Find your weekly hours in the left column and read across for your pro rata salary. The proportion column shows what fraction of full-time you’re working.
| Hours/week | Proportion of full-time | Annual pro rata | Monthly | Weekly | Hourly rate |
|---|---|---|---|---|---|
| 16 | 42.7% | £12,800 | £1,066.67 | £246.15 | £15.38 |
| 18 | 48.0% | £14,400 | £1,200.00 | £276.92 | £15.38 |
| 20 | 53.3% | £16,000 | £1,333.33 | £307.69 | £15.38 |
| 22 | 58.7% | £17,600 | £1,466.67 | £338.46 | £15.38 |
| 22.5 | 60.0% | £18,000 | £1,500.00 | £346.15 | £15.38 |
| 24 | 64.0% | £19,200 | £1,600.00 | £369.23 | £15.38 |
| 25 | 66.7% | £20,000 | £1,666.67 | £384.62 | £15.38 |
| 26 | 69.3% | £20,800 | £1,733.33 | £400.00 | £15.38 |
| 28 | 74.7% | £22,400 | £1,866.67 | £430.77 | £15.38 |
| 30 | 80.0% | £24,000 | £2,000.00 | £461.54 | £15.38 |
Two things to notice. First, the hourly rate never changes — £15.38 whether you work 16 hours or 30. That’s the whole point of pro rata: the rate is fixed, only the hours vary. Second, monthly pay is simply annual ÷ 12, which is what most UK employers pay.
Worked Example: 22 Hours at a £26,000 FTE
Tables are handy, but let’s walk through the maths so you can adapt it. You’ve been offered a role at £26,000 FTE, full-time is 37.5 hours, and you’ll work 22 hours.
- Proportion: 22 ÷ 37.5 = 0.5867 (58.67%)
- Annual: £26,000 × 0.5867 = £15,253.33
- Monthly: £15,253.33 ÷ 12 = £1,271.11
- Hourly: £15,253.33 ÷ 52 ÷ 22 = £13.33
Check: £13.33 × 37.5 × 52 = £26,000. The hourly rate reconciles to the FTE figure, so the calculation is correct.
Adapting the Tables to Your Salary
The £30,000 table scales linearly. To convert any figure for a different FTE salary, multiply by (your FTE ÷ 30,000):
- £24,000 FTE: multiply every figure by 0.8. So 20 hours/week = £16,000 × 0.8 = £12,800 a year.
- £35,000 FTE: multiply by 1.1667. So 24 hours/week = £19,200 × 1.1667 = £22,400 a year.
- £28,000 FTE: multiply by 0.9333. So 16 hours/week = £12,800 × 0.9333 = £11,946.67 a year.
Or skip the mental arithmetic entirely and run your exact numbers through our free pro rata salary calculator — it handles any combination of salary and hours instantly.
Common Part-Time Patterns and What They Mean
16 hours a week is a popular threshold: it’s the point where many people balance work with childcare or study, and historically it was tied to certain benefit entitlements. At 42.7% of full-time, it pays just under £12,800 on a £30k FTE.
20–22.5 hours covers the classic “three days a week” arrangement (three 7.5-hour days = 22.5 hours, exactly 60%). This is the most common part-time pattern in UK offices.
25–30 hours is sometimes called “almost full-time”. At 30 hours you’re at 80% of full-time pay — £24,000 on a £30k FTE — which for many people is the sweet spot between income and free time.
Compressed variations: some people work their 30 hours over four longer days rather than five shorter ones. The pay is identical — the calculator doesn’t care how you distribute the hours, only how many there are.
The 37-Hour and 40-Hour Variants
If your employer’s full-time week isn’t 37.5 hours, here are the key proportions for the most common alternatives:
| Hours/week | % of 37h full-time | % of 40h full-time |
|---|---|---|
| 16 | 43.2% | 40.0% |
| 20 | 54.1% | 50.0% |
| 22.5 | 60.8% | 56.3% |
| 25 | 67.6% | 62.5% |
| 30 | 81.1% | 75.0% |
Notice how the same 20-hour week is worth 54.1% of a 37-hour FTE but exactly 50% of a 40-hour FTE. This is why the full-time hours figure matters so much — always confirm it with the employer rather than assuming. When in doubt, ask for the full-time weekly hours in writing before you sign; it’s a small detail that changes every number downstream.
Worked Example: Term-Time Twist
Here’s a slightly trickier one. A school role pays £24,000 FTE (37 hours full-time), and you’ll work 25 hours a week, term-time only (39 weeks a year instead of 52).
First the hours proportion: 25 ÷ 37 = 0.6757. Then the weeks proportion: 39 ÷ 52 = 0.75. Combined: 0.6757 × 0.75 = 0.5068.
- Annual: £24,000 × 0.5068 = £12,162.16
- Monthly (spread over 12 months, as schools usually do): £12,162.16 ÷ 12 = £1,013.51
Term-time roles add a second fraction — the weeks worked — on top of the hours fraction. Miss it and you’ll overestimate your pay by a third.
What About Overtime on Top of Part-Time Hours?
The tables show your contracted pay. If you regularly work extra hours, those are usually paid at your normal hourly rate up to the full-time threshold — so a 20-hour worker doing 5 extra hours gets 5 × £15.38 = £76.90 extra that week on a £30k FTE. Only hours beyond full-time typically attract an overtime premium (often 1.5×), and some employers don’t offer premiums at all.
This matters when comparing offers: a 16-hour contract at a higher hourly rate with regular overtime available can out-earn a 20-hour contract at a lower rate. Work out both scenarios with the tables before deciding.
Using the Tables to Negotiate
The tables are also a negotiation tool. Suppose you’re offered 20 hours at a £28,000 FTE (£14,933 a year) but you want 24 hours. The table tells you 24 hours is worth £17,920 — a £2,987 difference. That’s a concrete number to put to the employer, far more persuasive than “I’d like more hours”.
Similarly, if an employer offers to cut your hours from 30 to 25, you can see instantly that it costs you £4,000 a year on a £30k FTE (£24,000 → £20,000). Knowing the exact figure helps you decide whether to accept, negotiate, or walk away.
One more tactic: compare the hourly rate, not just the annual figure. Two offers might look similar annually but differ per hour once the full-time baselines are accounted for. The employer with the shorter full-time week is effectively offering a better hourly deal.
Other working patterns: 20 hours a week · 24 hours a week · 30 hours a week · 37.5-hour week · 40-hour week · 2 days a week · 3 days a week · 4 days a week · 37.5 vs 40 hours · pro rata hours · days vs hours · examples by days per week
FAQs
How many hours a week counts as part-time in the UK?
There’s no legal definition. Anything below the employer’s full-time hours counts as part-time — so 30 hours is part-time where full-time is 37.5. The key number is always the employer’s own full-time figure, not some national standard.
Why is my hourly rate the same at 16 hours as at 30 hours?
Because pro rata scales pay with hours, not the rate. Your hourly rate is fixed by the FTE salary divided by full-time hours. Working fewer hours means fewer paid hours, never a lower rate — if an employer suggests otherwise, that’s a red flag.
Should I use 52 or 52.14 weeks in the calculation?
For 99% of purposes, 52. The 52.14 figure (365 ÷ 7) appears in some payroll systems and creates a ~0.3% difference. Unless your employer specifically uses it, stick with 52 for your own calculations — the gap on a £20,000 salary is only about £54 a year.
Do unpaid lunch breaks count in my weekly hours?
No. Only paid hours count. If you work 9am–5pm with an unpaid hour for lunch, that’s 35 hours a week, not 40. Check your contract for how the employer defines it.
Look Up Your Exact Figures
Tables get you close, but your precise salary deserves a precise calculation. Enter your FTE salary, full-time hours and weekly hours into our free pro rata salary calculator for your exact annual, monthly, weekly and hourly figures.