Pro Rata Salary Calculator
Calculate pro rata salary for part-time UK workers. Instant results for annual, monthly, weekly, and hourly rates.
Pro rata salary is calculated by dividing the part-time hours by full-time hours and multiplying by the full-time salary. For example, working 3 days a week (22.5 hours) instead of 5 (37.5 hours) on a £30,000 salary gives a pro rata salary of £18,000.
The gross annual salary for the full-time equivalent role.
Standard full-time hours (typically 37.5 or 40 in the UK).
The actual hours the part-time employee works per week.
Pro Rata Formula:
Holiday: 28 × (PT Hours / FT Hours)
Enter values above to calculate the pro rata salary.
What Does Pro Rata Mean?
Pro rata is a Latin term meaning “in proportion.” In the context of UK employment, it means calculating pay and benefits proportionally based on the hours worked compared to a full-time equivalent. It is most commonly used when an employee works part-time hours, starts or leaves a role mid-year, or transitions between full-time and part-time work.
Under the Part-Time Workers (Prevention of Less Favourable Treatment) Regulations 2000, part-time workers in the UK have the right to be treated no less favourably than comparable full-time workers. This includes pay rates, holiday entitlement, access to training, and pension rights — all calculated on a pro rata basis.
The Pro Rata Salary Formula
How to Calculate Pro Rata Salary
Here are three common scenarios showing how pro rata salary works in practice.
Annual salary: (22.5 / 37.5) × £30,000 = £18,000
Monthly: £18,000 / 12 = £1,500
Holiday: 28 × (22.5 / 37.5) = 16.8 days
Annual salary: (30 / 37.5) × £40,000 = £32,000
Monthly: £32,000 / 12 = £2,666.67
Holiday: 28 × (30 / 37.5) = 22.4 days
Annual salary: (37.5 / 37.5) × £35,000 = £35,000 (no change)
Holiday: Still 28 days (but each “day” is longer, so 22.4 compressed days is equivalent)
Compressed hours workers get the same pay because total hours are unchanged. Holiday may need adjusting based on “day” length.
How is pro rata holiday entitlement calculated?
Under the Working Time Regulations 1998, all UK workers are entitled to 5.6 weeks of paid annual leave. For a full-time worker doing 5 days per week, this equals 28 days (including bank holidays, if the employer chooses to include them).
Part-time workers receive the same 5.6 weeks, calculated pro rata. The simplest method is:
| Days Worked Per Week | Statutory Holiday (Days) | Typical Hours |
|---|---|---|
| 5 (full-time) | 28.0 | 37.5 or 40 |
| 4 | 22.4 | 30 or 32 |
| 3 | 16.8 | 22.5 or 24 |
| 2 | 11.2 | 15 or 16 |
| 1 | 5.6 | 7.5 or 8 |
Source: Working Time Regulations 1998
Frequently Asked Questions
How do you calculate pro rata salary?
Pro rata salary is calculated by dividing part-time hours by full-time hours, then multiplying by the full-time annual salary. The formula is: Pro Rata Salary = (Part-Time Hours / Full-Time Hours) × Full-Time Annual Salary. For example, if the full-time salary is £30,000 for 37.5 hours per week and you work 22.5 hours, your pro rata salary is (22.5 / 37.5) × £30,000 = £18,000.
What does pro rata mean for part-time workers?
Pro rata means “in proportion.” For part-time workers, it means your salary, holiday entitlement, and other benefits are calculated proportionally based on the hours you work compared to a full-time equivalent. If you work 3 days instead of 5, you receive 3/5 (60%) of the full-time salary and benefits. Part-time workers are protected by the Part-Time Workers Regulations 2000 and must not be treated less favourably than comparable full-time colleagues.
How is pro rata holiday entitlement calculated?
Pro rata holiday entitlement for part-time workers is calculated as 5.6 weeks multiplied by the number of days worked per week. For example, someone working 3 days per week gets 5.6 × 3 = 16.8 days of annual leave. This is the statutory minimum — your employer may offer more. Bank holidays can be included in or added on top of this entitlement.
Does pro rata affect pension contributions?
Yes, pro rata affects pension contributions because they are based on qualifying earnings. For the 2025/26 tax year, qualifying earnings are between £6,240 and £50,270. Your employer contributes a minimum of 3% and you contribute a minimum of 5% of your qualifying earnings. Since your pro rata salary is lower, the absolute amount of pension contributions will be proportionally lower, but the percentage rates remain the same.
How do you calculate pro rata for someone starting mid-year?
To calculate pro rata salary for a mid-year starter, divide the number of complete months remaining in the leave year by 12, then multiply by the annual salary. For example, if someone starts on 1 July with a £30,000 salary, they receive (6/12) × £30,000 = £15,000 for that partial year. Holiday entitlement is similarly pro-rated: 28 × (6/12) = 14 days for the remainder of the year.
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