How pro rata salary is calculated
A pro rata salary divides a full-time benchmark salary proportionally based on how much time you work compared to a full-time contract. In employment contracts, pro rata means in proportion to full-time equivalent hours.
When calculating by hours, your FTE ratio equals your actual weekly hours divided by standard full-time hours. Multiplying the full-time annual salary by this ratio gives your pro rata annual salary. Monthly pay is the annual figure divided by 12, and weekly pay is divided by 52.
When calculating by working days, the ratio compares your weekly days worked against a standard 5-day week. For term-time or partial-year contracts, the ratio reflects the number of paid weeks worked out of 52 weeks in a calendar year.
Worked example: Part-time employee on £35,000 FTE salary
Consider an employee offered a position advertised at £35,000 full-time equivalent per year. Standard full-time hours are 37.5 hours per week, but the employee agrees to work part-time at 22.5 hours per week.
First, work out the full-time equivalent proportion: 22.5 hours divided by 37.5 hours equals an FTE ratio of 0.60, or exactly 60.0% FTE.
Multiplying £35,000 by 0.60 gives a pro rata annual salary of £21,000.00 before tax. Dividing by 12 gives gross monthly pay of £1,750.00.
Across 52 weeks in the year, weekly pay equals £403.85 before tax, representing an annual salary reduction of £14,000.00 compared to a full-time schedule.
Part-time employee rights and term-time contracts
Under employment law in the UK and internationally, part-time employees have the legal right to no less favourable treatment than comparable full-time colleagues. This principle guarantees equivalent hourly pay rates, pension access, and pro rata holiday entitlement.
For school and educational workers on term-time contracts, pay is often calculated on 39 working weeks plus statutory paid annual leave allowance, then spread evenly into 12 equal monthly instalments throughout the calendar year.
All calculations display gross pay before statutory income tax, National Insurance or social security contributions, student loan deductions, and workplace pension contributions.
Inputs for the Pro rata calculator
Pro rata basis
Select whether to calculate your pro rata proportion using weekly hours, weekly days, or annual term-time weeks.
Full-time annual salary
The advertised or benchmark gross full-time equivalent (FTE) salary for the role before deductions.
Actual weekly hours
The number of hours you work each week on your part-time schedule.
Full-time weekly hours
The standard contracted weekly hours for a full-time worker in this position, usually 37.5 or 40 hours.
Actual weekly days
The number of days you work in a typical week on a days-based schedule.
Full-time weekly days
The standard full-time working week in days, usually 5 days.
Weeks worked per year
The contracted number of weeks worked annually, commonly 39 weeks for school term-time positions.
Full-time weeks per year
The standard total working and paid weeks in a full calendar year, usually 52 weeks.
CALCULATOR QUESTIONS
Pro rata calculator questions
What does pro rata salary mean?
Pro rata comes from the Latin meaning in proportion. A pro rata salary is what you earn when working part-time hours, calculated as a direct percentage of what a full-time worker in the same role earns.
How do you calculate pro rata pay from an annual salary?
Divide your actual weekly hours by full-time weekly hours to find your FTE ratio. Then multiply the full-time annual salary by that ratio to find your pro rata annual pay.
Does pro rata pay affect holiday entitlement?
Yes. Statutory annual leave is also calculated on a pro rata basis. For example, in the UK, full-time workers receive 28 days of statutory leave (5.6 weeks), while someone working 3 days a week receives 3 × 5.6 = 16.8 days.
Is pro rata salary calculated before or after tax?
Advertised pro rata salaries and calculator outputs are gross figures before income tax and social security contributions. Your actual take-home pay depends on your tax code and personal allowances.