Every pro-rata calculation divides by full-time hours — but what counts as full time UK hours is not a single number. It is 37.5 in the NHS, 37 in the civil service, 40 on many shop floors, and 35 in plenty of London offices. Because the baseline changes the entire calculation, understanding the benchmarks across sectors is essential for anyone checking their pay or setting it.
There is no single legal definition
UK law does not define full-time working hours (outside specific rules like the 48-hour Working Time limit and minimum wage calculations). “Full-time” is whatever the employer, sector agreement or contract says it is. That is why two people can both work 35 hours a week while one is full-time and the other is 0.93 FTE.
What matters for your pay is the contractual baseline at your employer — not a national average, not what your friend works, and not what a job advert implies.
The main sector benchmarks
Here are the full-time standards you will encounter most often in the UK:
| Sector / employer | Full-time week | Notes |
|---|---|---|
| NHS (Agenda for Change) | 37.5 hours | Set nationally; part-timers use 37.5 as the divisor |
| Civil Service | 37 hours | Standard across most departments |
| Local government (NJC) | 37 hours | The “Green Book” standard |
| Police staff | 37 hours | Set by Police Staff Council |
| Teachers (England) | 32.5 directed hours + PPA | Often quoted as 37+ in practice; directed time is 1,265 hours/year |
| Universities (academic) | 35–37 hours | Varies by institution; fractional contracts common |
| Private-sector offices | 35–40 hours | 35 common in London; 37.5–40 elsewhere |
| Retail and hospitality | 39–45 hours | Often 40+; overtime rules vary |
If your employer follows a national agreement (NHS, civil service, local government), the baseline is fixed and published. In the private sector, it is whatever your contract states — read it carefully.
Why the baseline changes your pay
The same weekly hours produce different salaries under different baselines. Take a £32,000 FTE salary and an employee working 28 hours a week:
| Full-time baseline | FTE fraction | Pro-rata salary |
|---|---|---|
| 35 hours | 0.8000 | £25,600 |
| 37 hours | 0.7568 | £24,216 |
| 37.5 hours | 0.7467 | £23,893 |
| 40 hours | 0.7000 | £22,400 |
The gap between the 35-hour and 40-hour baselines is £3,200 a year for identical hours worked. This is why “what counts as full-time” is not an abstract question — it is worth thousands of pounds. When comparing job offers, always convert to the hourly rate (annual salary ÷ (weekly hours × 52)) so you compare like with like.
Full-time vs the 48-hour Working Time limit
Do not confuse the contractual full-time baseline with the legal maximum. The Working Time Regulations 1998 cap average weekly working time at 48 hours (averaged over 17 weeks), though workers can opt out in writing. The 48-hour figure is a health-and-safety ceiling, not a pay baseline — nobody’s pro-rata fraction is calculated against 48 hours.
Similarly, the National Minimum Wage uses actual hours worked, not a notional full-time week. A part-timer’s compliance check is: (gross pay ÷ actual hours worked) ≥ minimum wage. The FTE baseline is irrelevant to that test.
How employers should state the baseline
Best practice for offer letters and contracts is to state all three figures explicitly:
“Your salary is £24,216 per annum, based on a full-time equivalent salary of £32,000 for 37 hours per week. You will work 28 hours per week (0.7568 FTE).”
This single sentence lets the employee verify the entire calculation. Vague wording like “£24,216 pro rata” invites disputes, because the employee cannot check which baseline was used. If your contract lacks the baseline, ask HR to confirm it in writing — you are entitled to understand how your pay is derived. And if you want to test the numbers yourself, our free pro rata salary calculator lets you plug in any baseline and see the result instantly.
Part-time thresholds: when does part-time become full-time?
There is no legal tripwire where part-time “becomes” full-time at a specific hour count. Someone working 36 of 37.5 hours is still part-time (0.96 FTE) with pro-rata treatment. However, some practical thresholds matter:
- Overtime rules usually change at the full-time baseline: hours up to the baseline are paid at the normal rate, hours beyond it may attract premiums.
- Benefit eligibility (e.g. some employer pension top-ups, private medical cover) sometimes requires a minimum FTE such as 0.5 — check the scheme rules.
- Statutory rights like unfair dismissal protection and maternity rights do not depend on full-time status at all.
If you are close to the baseline — say 35 of 37.5 hours — it is worth asking whether the role could simply be designated full-time, since the administrative difference is negligible but the perception (and sometimes the benefits) differ.
Comparing offers across different baselines
Job adverts sometimes quote the FTE salary and sometimes the actual pro-rata salary, and they do not always say which. When comparing two part-time offers with different baselines, convert everything to hourly rates:
Worked example: Offer A: £22,000 for 25 hours/week where full-time is 35 hours. Offer B: £21,000 for 25 hours/week where full-time is 37.5 hours.
- Offer A hourly: £22,000 ÷ (25 × 52) = £22,000 ÷ 1,300 = £16.92
- Offer B hourly: £21,000 ÷ (25 × 52) = £21,000 ÷ 1,300 = £16.15
Offer A pays more per hour despite the similar headline figures. But also check the FTE rates: Offer A implies £30,800 FTE; Offer B implies £31,500 FTE — so Offer B’s employer actually values the role more highly, and a future hours increase would be worth more there. Both numbers tell you something useful.
Table: what 25 hours a week is worth at different FTE salaries (hourly)
| FTE salary | 35h baseline hourly | 37.5h baseline hourly | 40h baseline hourly |
|---|---|---|---|
| £28,000 | £15.38 | £14.36 | £13.46 |
| £32,000 | £17.58 | £16.41 | £15.38 |
| £36,000 | £19.78 | £18.46 | £17.31 |
Notice that £28,000 on a 35-hour baseline gives the same hourly rate as £32,000 on a 40-hour baseline (£15.38). Baselines matter as much as salaries.
What to do if your employer’s baseline seems unusual
Most baselines fall between 35 and 40 hours. If yours sits outside that range, ask why:
- A baseline above 40 for office work is unusual — check it is genuinely contractual and not an error.
- A baseline below 35 may reflect generous terms (common in some charities and universities) — good for you, since your fraction will be higher.
- If the baseline changed (e.g. after a TUPE transfer) without your pro-rata pay being recalculated, raise it — your fraction changed and so should your salary.
Whatever the baseline, it must be applied consistently to everyone in the same group. Different baselines for people doing the same job, without objective justification, can amount to less favourable treatment of part-timers.
More FTE guides: what FTE means · FTE and salary · FTE percentage to pay · 0.2 FTE salary · 0.5 FTE salary · 0.8 FTE salary
FAQs
What counts as full-time hours in the UK?
There is no single legal figure. Common benchmarks are 37.5 hours (NHS), 37 hours (civil service and local government) and 35–40 hours in the private sector. Your contract defines what counts as full-time for your pay.
Is 30 hours a week full-time in the UK?
It depends on the employer’s baseline. Where full-time is 37.5 hours, 30 hours is 0.8 FTE — part-time. Where full-time is 35 hours, it is 0.86 FTE — still part-time. Only if the baseline were 30 hours would it be full-time.
Does the 48-hour working week affect pro-rata calculations?
No. The 48-hour Working Time limit is a health-and-safety ceiling, not a pay baseline. Pro-rata fractions are always calculated against the contractual full-time hours, typically 35–40.
How do I compare two part-time jobs with different full-time baselines?
Convert both to hourly rates: annual salary ÷ (your weekly hours × 52). The hourly rate cuts through baseline differences and shows which job genuinely pays more per hour worked.
Know your baseline, know your worth
The full-time baseline is the quiet number that controls your entire pro-rata calculation. Learn what it is at your employer, check it appears in your contract, and use it to verify every payslip and compare every offer. Ten minutes with the right baseline beats hours of guesswork.
To see exactly what any baseline means for your pay, try the free pro rata salary calculator — enter the FTE salary, set the full-time hours, and dial your hours up and down to watch the result change.
A final note on job adverts
When a job advert says “£30,000 pro rata”, it is quoting the FTE salary — your actual pay will be lower unless you work full-time. When it says “£18,000 actual salary”, that is what lands in your bank (before tax). If the advert is ambiguous, ask the recruiter two questions: what is the FTE salary, and what are full-time hours? With those answers and your contracted hours, you can work out the real figure before you ever apply.