UK Pro Rata Salary Calculator [Free]: Part-Time Pay 2026

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Pro Rata Salary Calculator

Calculate pro rata salary for part-time 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.

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Calculate Pro Rata Salary

Enter the full-time salary and hours to calculate the part-time equivalent.

Full-Time Annual Salary ($)

The gross annual salary for the full-time equivalent role.

Full-Time Hours Per Week

Standard full-time hours (typically 37.5 or 40).

Part-Time Hours Per Week

The actual hours the part-time employee works per week.

Pro Rata Formula:

(PT Hours / FT Hours) × FT Salary

Holiday: 28 × (PT Hours / FT Hours)

Your Pro Rata Salary

Enter values above to calculate the pro rata salary.

Understanding pro rata

What Does Pro Rata Mean?

Pro rata is a Latin term meaning “in proportion.” In 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.

Part-time workers generally have the right to be treated no less favourably than comparable full-time workers. This includes pay rates, holiday entitlement, access to training, and retirement benefits — all calculated on a pro rata basis.

The Pro Rata Salary Formula

Pro Rata = (PT Hours / FT Hours) × FT Salary

Worked examples

How to Calculate Pro Rata Salary

Here are three common scenarios showing how pro rata salary works in practice.

Example 1: 3-Day Week

Emma works 22.5 hours per week (3 days) on a £30,000 FTE salary.

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

Example 2: 4-Day Week

David works 30 hours per week (4 days) on a £40,000 FTE salary.

Annual salary: (30 / 37.5) × £40,000 = £32,000

Monthly: £32,000 / 12 = £2,666.67

Holiday: 28 × (30 / 37.5) = 22.4 days

Example 3: Compressed Hours (Full-Time)

Priya works 37.5 hours over 4 longer days. Same hours, different schedule.

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.

Holiday entitlement

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

Common questions

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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