Understanding Pro Rata Salary

When you're offered a part-time or term-time-only role, employers often quote a 'pro rata' salary – a fraction of the full-time equivalent. Knowing how to work out pro rata salary from an hourly rate is essential for comparing job offers and understanding your true earnings.

Pro rata simply means 'in proportion'. If a full-time role pays £30,000 for 37.5 hours per week, and you work 20 hours per week, your pro rata salary is (20 ÷ 37.5) × £30,000 = £16,000. But many job adverts quote an hourly rate instead, so you need to convert that into an annual figure.

The Basic Conversion Formula

The standard way to convert an hourly rate to an annual salary is:

Annual salary = hourly rate × hours per week × 52 weeks

This assumes you are paid for 52 weeks a year (including holiday pay if it's rolled up). For example, at the National Living Wage of £12.21 per hour (2025 rate) and a 37.5-hour week:

£12.21 × 37.5 × 52 = £23,809.50 per year

If you work part-time, say 20 hours per week:

£12.21 × 20 × 52 = £12,698.40 per year

That is your pro rata salary based on the full-time equivalent of 37.5 hours.

What Hours Assumption Should You Use?

There is no single legal definition of full-time hours in the UK. The Office for National Statistics (ONS) defines full-time as more than 30 paid hours per week (or 25+ for teaching professions). However, many employers use 35, 37.5, or 40 hours. The NHS, for example, uses 37.5 hours as standard for Agenda for Change roles. Our salary calculator lets you adjust the hours per week to match your contract.

When you see a job advertised as '£25,000 pro rata', always check what full-time hours the employer assumes. If it's 37.5 hours, your part-time salary is straightforward to calculate. If the advert only gives an hourly rate, you can work backwards: full-time equivalent salary = hourly rate × full-time hours × 52.

UK Benchmarks for Hourly and Annual Pay

The latest ONS Annual Survey of Hours and Earnings (ASHE) for 2025 gives these median figures:

• Full-time employees: median weekly earnings £766.60, median annual earnings £39,039, median hourly earnings £19.67
• Part-time employees: median weekly earnings £280.00

Using the 37.5-hour week assumption, the median full-time hourly rate of £19.67 gives an annual salary of £19.67 × 37.5 × 52 = £38,361 – close to the ONS annual figure of £39,039. The small difference is because ONS annual figures include employees who have been in post for a year or more and may include pay rises or overtime.

For part-time workers, the median weekly earnings of £280 equate to roughly £14,560 per year (52 weeks). If you work 20 hours per week, that's an hourly rate of about £14.00 – higher than the National Living Wage, reflecting the fact that part-time workers are spread across all occupations.

National Living Wage and Minimum Wage Rates

The government sets minimum hourly rates that apply to almost all workers. For 2025, the rates were:

• Age 21 and over (National Living Wage): £12.21 per hour
• Age 18–20: £10.00 per hour
• Age 16–17: £7.55 per hour
• Apprentices: £7.55 per hour

For 2026/27, the National Living Wage rises to £12.71 per hour. When working out pro rata salary, your hourly rate must never fall below the applicable minimum wage, regardless of how many hours you work.

Pro Rata for Part-Time vs Full-Time

If you are moving from a full-time to a part-time role, your pro rata salary is simply your full-time salary multiplied by the fraction of hours you will work. For example, if you currently earn £35,000 for 37.5 hours and drop to 30 hours:

Pro rata salary = (30 ÷ 37.5) × £35,000 = £28,000

If you are starting a new job with an hourly rate, calculate your annual salary first, then compare it to the full-time equivalent for that role. Many job sites list both the hourly rate and the full-time equivalent annual salary – use the latter to compare across roles.

NHS and Public Sector Examples

The NHS publishes annual and hourly pay scales for each band. For 2026/27, the lowest band (Band 1) starts at around £22,383 per year (full-time, 37.5 hours), which works out at about £11.48 per hour. Higher bands include Higher Cost Area Supplements (London weighting) that increase the hourly rate. If you work part-time in the NHS, your salary is calculated pro rata using the full-time band rate and your contracted hours.

Important Caveats

• Overtime: The conversion formula assumes no overtime. If you regularly work extra hours, your actual annual earnings will be higher.
• Holiday pay: Some employers pay holiday pay separately or include it in the hourly rate. Check your contract.
• London weighting: Jobs in London and the South East often include an additional allowance. This is not captured by a simple hourly-to-annual conversion.
• Salary sacrifice: Benefits like pension contributions or cycle-to-work schemes reduce your taxable pay but not your contractual salary.

Always use your contractual hours and rate, and refer to official guidance on GOV.UK for the latest minimum wage and tax thresholds.

Using Our Tools

To make the calculation easy, try our Hourly to Salary converter. You can enter your hourly rate, weekly hours, and see your annual, monthly, and weekly pay instantly. For more context on UK earnings, browse our salary data pages, which include median pay by occupation and region.

Summary

To work out pro rata salary from an hourly rate:

1. Confirm your contracted hours per week.
2. Multiply hourly rate × hours × 52 to get annual salary.
3. If comparing to a full-time role, divide your annual salary by the full-time equivalent salary (or use the fraction of hours).
4. Check that your hourly rate meets the National Living Wage or Minimum Wage.
5. Account for any location allowances or overtime.

Understanding pro rata pay helps you negotiate fairly and budget accurately, whether you're working part-time, job-sharing, or on a reduced-hours contract.