The Number That Catches Term-Time Workers Off Guard
Most people who work term time assume their salary is simply a percentage of the full-time rate — roughly two-thirds of the year, so roughly two-thirds of the pay. That thinking is close, but it misses something important. Your actual term-time pro rata salary depends on two separate ratios working together: how many weeks you work versus the full year, and how many hours per week you work versus the full-time standard. Get either one wrong and the number you land on won’t match your payslip.
Teaching assistants, school administrators, lunchtime supervisors, and term-time support staff run into this constantly. Someone starts a new role, does a rough calculation in their head, and ends up surprised when HR sends over the contract. That gap between expectation and reality is usually caused by one of two things — either the hours ratio wasn’t factored in, or the total weeks figure used was wrong.
This calculator handles both. You enter your full-time equivalent salary, the number of weeks you actually work, your contracted hours, and the full-time hours for the role. The result you get back is the correct term-time pro rata figure — not an estimate.
How the Pro Rata Term Time Calculation Actually Works
The standard approach used by most UK schools, local authorities, and payroll teams follows a two-ratio method. It’s not complicated once you see how the parts fit together, but it’s easy to shortcut incorrectly if you’re doing it by hand.
Step-by-Step: Using This Calculator
- Enter the full-time annual salary for the role — this is the figure the job would pay if worked 52 weeks at full-time hours.
- Enter the number of weeks you actually work during the school year. Most teaching support roles sit somewhere between 38 and 40 weeks, though the exact number depends on your employer’s term structure.
- Set the total weeks in the year. The default is 52, which is correct for the vast majority of calculations.
- Enter your holiday entitlement in days — this will also be scaled down pro rata so you can see what you’re actually entitled to.
- Enter your contracted hours per week and the full-time hours for the role. These two figures produce the hours ratio.
- Choose how you want to see the result — as an annual figure, monthly pay, weekly, or daily.
- Hit Calculate. The breakdown shows both ratios and the final pro rata salary.
The Formula Behind the Result
The calculation runs in two stages. First, the hours ratio: your contracted hours divided by the full-time hours for the role. If full-time is 37 hours and you work 32.5, your hours ratio is 0.878. Second, the weeks ratio: your term-time weeks divided by the total weeks in the year. If you work 39 weeks out of 52, your weeks ratio is 0.75.
Multiply the full-time salary by both ratios and you have your term-time pro rata salary.
Breaking Down Each Part of the Formula
The hours ratio exists because term-time pro rata isn’t just about weeks — it’s also about whether you’re working part-time hours within those weeks. A school-based role might be 32.5 contracted hours against a 37-hour full-time standard. That difference matters. Ignoring it is one of the most common mistakes people make when trying to calculate pro rata salary term time manually.
The weeks ratio is the other half. It compares your actual working weeks to the full year. The GOV.UK guidance on school teachers’ pay and conditions uses this same principle when setting out how part-year working is treated for pay purposes.
Worked Example With Real Numbers
Take a teaching assistant role with a full-time equivalent salary of £28,000 per year. The role is 32.5 hours per week against a 37-hour full-time standard. The post is term time only — 39 weeks per year. Holiday entitlement for the full-time role is 25 days.
Hours ratio: 32.5 ÷ 37 = 0.8784. Weeks ratio: 39 ÷ 52 = 0.75. Pro rata annual salary: £28,000 × 0.8784 × 0.75 = £18,446. Monthly pay: £18,446 ÷ 12 = £1,537. Pro rata holiday entitlement: 25 × 0.8784 × 0.75 = 16.47 days.
Where This Matters Beyond the Obvious
The most common use is verifying a job offer. When you get a contract that quotes a term-time salary, running it back through the formula confirms whether the employer has applied the ratios correctly. It happens more often than you’d think — payroll errors on term-time contracts are a known issue, particularly in larger local authority schools where salary calculations are processed centrally.
When Your Start or End Date Falls Mid-Term
If you start or leave a role partway through a term, your entitlement is calculated on actual weeks worked rather than full terms. The same formula applies, but with a fractional weeks-worked figure. This is also where rounding becomes important — always round to two decimal places at each stage rather than rounding at the end, to avoid a small but cumulative error in the final figure.
What Changes When Contracted Hours Change
If your contracted hours increase — say, from 20 hours to 25 hours per week — your term-time pro rata salary doesn’t just go up by a flat percentage of the difference. Because the hours figure feeds directly into the first ratio, the change ripples through the entire calculation. Running it fresh through the calculator every time your hours change is quicker than trying to adjust mentally.
Three Things That Throw Off a Manual Calculation
Using the Wrong Weeks Figure
Some people use 365 days divided by 7 (52.18 weeks) instead of a flat 52. Both are defensible depending on what your employer uses, but mixing them gives you a wrong answer. Check your contract or ask HR which figure they apply — then use the same one.
Forgetting to Scale Holiday Entitlement
Your term-time pro rata holiday entitlement is calculated separately — it isn’t included in the weeks-worked figure. If you forget to scale your holidays, you’ll either overestimate what you’re owed or underestimate it, neither of which is helpful when you’re planning leave or negotiating terms.
Applying Only One Ratio
This is the most frequent mistake. Someone calculates the weeks ratio correctly — 39 ÷ 52 = 75% — and then just applies that to the full salary without considering the hours ratio. If you work part-time hours, that single-ratio answer will always be higher than your actual pay.
Questions People Actually Ask About Term Time Pro Rata Pay
What does term time only mean on a salary?
It means you’re employed to work only during school terms, not throughout the full year. Your salary is calculated pro rata based on the weeks you work compared to a full 52-week year. The Chartered Institute of Payroll Professionals provides detailed guidance on how part-year contracts should be treated for pay purposes.
Is 39 weeks the standard for term-time working?
39 weeks is the most commonly used figure for school support staff in England. It accounts for 38 weeks of teaching time plus one week of training or INSET days. But this varies by school and local authority — some roles are 38 weeks, others are 40. Always use the exact figure in your contract rather than assuming.
Why does my monthly pay look the same every month if I only work term time?
Most schools pay term-time staff on an averaged basis — your total annual pro rata salary is divided by 12 and paid in equal monthly instalments. This means you receive pay during school holidays even though you’re not working. It doesn’t change the total amount you earn; it just smooths the payments across the year.
How do I calculate pro rata salary term time if I work part-time hours?
You need both the hours ratio and the weeks ratio. Divide your contracted hours by the full-time hours to get the first ratio. Divide your term-time weeks by 52 to get the second. Multiply the full-time salary by both ratios. This calculator does that automatically and shows the breakdown so you can verify each step.
Does pro rata affect my pension contributions?
Yes — if your pension contributions are calculated as a percentage of salary, they’ll be based on your reduced pro rata pay rather than the full-time equivalent. If you’re in a defined benefit scheme like the Local Government Pension Scheme, the pro rata salary is also the figure used when calculating pensionable pay.
Can I use this calculator for a school administrator or lunchtime supervisor role?
Yes. The formula applies to any term-time only role regardless of job title. Teaching assistants, site supervisors, office staff, and catering workers on term-time contracts all use the same two-ratio calculation. The only variables that change are the weeks worked and contracted hours.
What if my contract says I work 38 weeks but also includes training days?
Add the training days to your working weeks. If you work 38 term weeks plus 5 training days, that’s an additional week — so your actual total is 39 weeks. Use 39 in the calculation. Some contracts specify this explicitly; others don’t, so check the wording carefully.
Does this calculator work for Scotland and Wales?
The formula is the same regardless of which part of the UK you’re in. Term structures vary slightly — Scottish schools often have different term lengths to England — so the number of weeks you enter will differ, but the calculation method is identical. Enter your actual contracted weeks and the tool handles the rest.
What Do You Do With the Result?
Cross-check it against your contract or job offer letter. If the figure in your contract is noticeably different from what this calculator produces, it’s worth asking HR to walk through how they calculated it. Payroll errors on term-time contracts are not rare, and most employers will correct a mistake when it’s pointed out with the right numbers behind it. Keep a note of the inputs you used so you can show your working clearly.