Work and pay
£30,000 pro rata: the salary behind the advert
The two small words after the salary can make a large difference to the offer. But a shorter week may cost less in take-home pay than the cut in hours suggests.
An advert offers £30,000. The role is three days a week. Then comes “pro rata”. For a job with a 37.5-hour full-time week, those three equal days bring the actual salary down to £18,000 a year. That is £1,500 gross a month and, on our standard 2026/27 calculation, £1,373.30 after tax and NI.
The full-time salary tells you the rate the employer is offering. The actual salary tells you what the contract pays. Both belong in a useful job advert; neither, on its own, tells you what will arrive in your bank account.
Start with the hours, not the number of days
The pro-rata salary calculation is straightforward when the contract covers the whole year:
Full-time salary × your weekly hours ÷ full-time weekly hours
For the advert above, £30,000 × 22.5 ÷ 37.5 gives £18,000. The hours ratio is 0.6, or 0.6 full-time equivalent (FTE). Four equal days would be 0.8 FTE: 30 hours and £24,000 a year.
Counting days is a shortcut that works only when the days are equal. Two long shifts and one short shift need an hours calculation. A compressed four-day week can still contain all 37.5 hours, in which case this formula leaves annual salary unchanged.
If an advert says “£30,000 FTE; £18,000 actual”, enter £30,000 as the full-time salary above. Using £18,000 in that field would cut the salary twice. Before accepting an offer, ask the employer to confirm the actual annual gross salary in writing.
Part-time work accounts for more than one in four employee jobs. ONS put the share at 28.0% in April 2025, compared with 27.2% a year earlier. These are provisional job estimates, not a count of people requesting a shorter week. ONS: Employee earnings in the UK, 2025.
What does a three-day or four-day week leave after tax?
Giving up a fifth of your hours does not necessarily mean giving up a fifth of your spending money. The Personal Allowance remains available, while the salary surrendered includes money that would have gone to tax and NI.
On £30,000 full time, four equal days retain 82.8% of take-home pay for 80% of the hours. Three days retain 65.6% for 60% of the hours. The difference is useful when a rough “I will lose 20%” estimate makes a change appear unaffordable.
| Working week¹ | Hours | Annual gross | Monthly net | Net pay retained |
|---|---|---|---|---|
| 2 days | 15 | £12,000 | £1,000.00 | 47.8% |
| 3 days | 22.5 | £18,000 | £1,373.30 | 65.6% |
| 4 days | 30 | £24,000 | £1,733.30 | 82.8% |
| 5 days | 37.5 | £30,000 | £2,093.30 | 100.0% |
PayPrecise full-year calculations using HMRC’s 2026/27 rates: England, Wales or Northern Ireland; standard Personal Allowance; NI category A; no pension or student loan. Monthly net is annual net ÷ 12. ¹ Days assume equal 7.5-hour shifts. Payslip rounding can differ.
The price of one day back
The monthly cost rises with salary, but it does not rise in a straight line. Moving from 37.5 to 30 hours gives these results:
| Full-time salary | Full-time net/month | Four-day net/month | Monthly reduction |
|---|---|---|---|
| £30,000 | £2,093.30 | £1,733.30 | £360.00 |
| £40,000 | £2,693.30 | £2,213.30 | £480.00 |
| £60,000 | £3,779.78 | £3,173.30 | £606.48 |
The same 2026/27 assumptions apply to both tables.
At £60,000, the gross cut is £1,000 a month. The take-home cut is £606.48 because the hours reduction also removes some higher-rate earnings. At £30,000, one fewer equal working day costs £360 a month in this model.
That is the salary side of the decision. A day with less childcare or commuting may reduce the household cost; a change in benefit entitlement may move it again. Set those amounts beside the net-pay reduction rather than treating the FTE percentage as a complete budget. Use the household income calculator to compare your combined income after tax with a household-size benchmark.
Term-time pay has a second fraction to check
For a school-year job, hours are only half the calculation. The contract also needs to say how many weeks are paid. Worked weeks and paid weeks can differ because holiday pay may be included.
Take the same £30,000 full-time salary and 22.5 hours, but a contract confirming 44 paid weeks. The annual calculation becomes:
£30,000 × 22.5 ÷ 37.5 × 44 ÷ 52 = £15,230.77
Paid in 12 equal instalments, that would be £1,269.23 gross each month. An employer may spread term-time salary across school holidays, so the days worked in a month need not explain that month’s payment.
The contractual paid-week figure is the one to use. Entering 38 simply because the school has 38 teaching weeks can leave out holiday pay. Reducing a quoted “actual term-time salary” for weeks again can understate it a second time. If the employer uses a different annualisation convention, its contractual calculation takes priority over this 52-week comparison.
For an ordinary year-round salaried job, keep 52 paid weeks. Paid annual leave is already included in annual salary.
Two £24,000 offers. A 7.5-hour difference.
Equal annual salaries can buy very different amounts of your time. Consider two year-round offers, both paying £24,000 actual salary:
Offer A: 30 hours a week
- Full-time equivalent¹
- £30,000
- Gross hourly equivalent²
- £15.38
Offer B: 22.5 hours a week
- Full-time equivalent¹
- £40,000
- Gross hourly equivalent²
- £20.51
¹ A 37.5-hour full-time week. ² Annual salary ÷ weekly hours ÷ 52 paid weeks.
With the same deductions, the two salaries produce the same take-home. Offer B requires 7.5 fewer paid hours each week. That is an entire standard working day whose value disappears if the comparison stops at annual salary.
Use the salary-to-hourly calculator to compare rates. Then add commuting and unpaid time in True Wage. A shorter contracted week can lose some of its advantage if the role routinely needs work outside those hours.
Part-time worker protections cover comparable treatment, including pay rates, subject to objectively justified differences. The FTE figure helps make that comparison visible.
The deductions that do not shrink neatly with your hours
A full-time payslip multiplied by 0.6 will not reliably predict three-day take-home. Deductions have thresholds and different contribution rules.
At £30,000, a Plan 2 student loan generates an estimated £55.35 annual repayment in our 2026/27 example before any pension. At £18,000, the salary is below the Plan 2 threshold and the modelled repayment is zero. Applying 60% to the old repayment would invent a deduction that is no longer due on that annual salary.
A pension set at a percentage of actual salary usually falls with pay. A fixed £100 monthly contribution stays £100. A qualifying-earnings scheme uses only the eligible slice, so its contribution cannot be predicted simply by multiplying the old amount by FTE.
Thinking of adding a pension contribution after reducing your hours? The pension salary sacrifice calculator compares the amount invested with the take-home cost. Enter your actual part-time salary before sacrifice, rather than the full-time equivalent.
The calculator’s tax and pension settings apply the same chosen arrangement to both salaries: fixed contributions stay fixed and percentage contributions are recalculated. If a second job already uses your allowance, check the salary calculator’s supported tax-code mode; a standard allowance for each job would overstate the money available.
Before you sign a part-time contract
Does “£30,000 pro rata” mean I will earn £30,000?
Usually it is the full-time salary before deductions. At 22.5 hours out of a 37.5-hour week, it becomes £18,000 gross a year over 52 paid weeks. Check whether the advert also gives an actual salary; that figure may already have been reduced.
How much is a £30,000 salary at 0.8 FTE?
It is £24,000 gross a year, or £2,000 gross a month, for a year-round contract. Estimated 2026/27 take-home is £1,733.30 a month in England, Wales or Northern Ireland with the standard allowance, employee NI category A and no pension or loan.
How do I work out salary for a three-day week?
If full time means five equal-length days, three days is 0.6 FTE. Multiply the full-time salary by 0.6. A £30,000 full-time salary becomes £18,000 gross; a 37.5-hour week becomes 22.5 hours. Use hours if the days have different lengths.
Should I subtract paid holidays from the 52 weeks?
For a normal year-round salaried contract, keep 52 paid weeks: paid leave is included in annual pay. A term-time or part-year contract needs the employer’s contractual paid-week figure, which may include holiday pay as well as worked weeks.
What if I reduce my hours halfway through the tax year?
The calculator shows a complete year at the new working pattern. Your first reduced-hours payslip can differ because payroll also takes account of earnings and tax earlier in the year. Use the result for the ongoing pay level, rather than the exact transition month.