Reviewed for UK readers: September 2026.
Sometimes you know the part-time salary but not the full-time equivalent. A reverse pro rata calculation solves that: full-time salary = pro rata salary ÷ FTE fraction. You can also test the figures in our pro rata calculator by entering the resulting full-time salary and your working hours.
This is particularly useful when comparing vacancies that advertise only “actual salary” or when checking whether two part-time offers sit on the same underlying grade.
Quick answer
- Full-time equivalent = actual pro rata salary ÷ FTE.
- £24,000 at 0.8 FTE implies £30,000 FTE.
- Find FTE from hours if it is not stated.
- Term-time-only actual salary may require reversing both hours and paid-weeks factors.
Reverse calculation using FTE
If actual annual salary is £21,000 at 0.6 FTE, full-time equivalent is £21,000 ÷ 0.6 = £35,000. If actual salary is £32,000 at 0.8 FTE, FTE salary is £40,000.
Find FTE from hours first
If the employee works 28 hours and full time is 35, FTE is 28 ÷ 35 = 0.8. An actual salary of £27,200 therefore implies a full-time salary of £34,000.
Term-time warning
A term-time actual salary can reflect both weekly hours and paid weeks. Dividing only by the hours FTE can understate the underlying full-year equivalent. You need the employer’s term-time factor to reverse the calculation accurately.
Comparing job offers
Convert both offers to an FTE salary, then separately compare contracted hours, paid weeks, pension, holiday and other benefits. This avoids treating a higher actual salary as automatically better when it also requires more hours.
Rounding
Employers may round FTE percentages or payroll figures, so a reverse calculation can differ slightly from the published full-time salary. Small differences are normal; large differences should be checked with HR.
Common pro rata salary mistakes
The most common errors are using the wrong full-time comparator, treating unequal days as equal, confusing gross and net salary, and applying a term-time reduction to a role that is already quoted as an actual salary. Always identify the full-time salary, full-time hours and your contracted hours before calculating.
If the employer provides an official FTE percentage, use it as a cross-check. Small differences can come from rounding; larger differences usually mean another factor such as paid weeks or an allowance is involved.
Use the calculator
For a quick gross salary estimate, use the Pro Rata Calculator UK. Enter the full-time salary and your hours, days or FTE, then compare the result with your contract or payroll figure.
Frequently asked questions
What is £24,000 at 0.8 FTE full time?
£24,000 ÷ 0.8 = £30,000 full-time equivalent.
What is £18,000 at 0.6 FTE full time?
£18,000 ÷ 0.6 = £30,000 FTE.
Can I reverse a term-time salary the same way?
Only if you also know and reverse any term-time paid-weeks factor.
Why does my reverse result differ from the advert?
Rounding, allowances, term-time factors or use of a different full-time comparator can create differences.
This article is general information, not personalised legal, tax or payroll advice. Employment contracts, collective agreements and individual circumstances can change the correct result.
Important: This article is general information, not personalised financial, tax, payroll, employment or legal advice. Check important figures against your contract and current official guidance.