Pro rata salary: how part-time and part-year pay is worked out

“30,000 pro rata” in a job advert does not mean you will earn 30,000. It means 30,000 is the full-time salary, and you will be paid the proportion that matches the hours or time you actually work. Pro rata is Latin for “in proportion”.

Part-time hours

Pro rata salary = full-time salary × (your hours ÷ full-time hours)

A job at 30,000 for a 37.5-hour week, worked for 22.5 hours: 30,000 × 22.5 ÷ 37.5 = 18,000 a year. Three days of a five-day week works the same way: 30,000 × 3 ÷ 5 = 18,000.

Make sure you know the full-time hours the employer uses. 30,000 pro rata for 20 hours is 16,000 if full time is 37.5 hours, but 15,000 if full time is 40.

Check the hourly rate

Pro rata pay should give the same hourly rate as the full-time job. The Salary Calculator shows it: enter 18,000 a year at 22.5 hours a week, then 30,000 at 37.5 hours. Both come to about 15.38 an hour. If a part-time offer works out lower per hour than the full-time rate, ask why.

Starting or leaving part-way through the year

Pay for part of a year is pro-rated by time. Monthly-paid staff usually just receive their monthly salary for each full month worked, plus a part-month for the first and last month. A part-month is often worked out by days:

Part-month pay = monthly salary × (days worked ÷ days in that month)

Some employers divide by working days instead of calendar days. Both are common; your contract or payroll policy says which.

Holiday entitlement

Paid holiday is usually pro-rated too. In the UK, for example, the statutory minimum is 5.6 weeks a year. For someone working three days a week, that is 5.6 × 3 = 16.8 days. Part-year workers get the same proportion of the year: starting on 1 October in a January-to-December holiday year gives three twelfths of the annual entitlement.

Benefits and bonuses

• Bonuses set as a percentage of salary are naturally pro-rated. Fixed-amount bonuses may or may not be; check.
• Pension contributions as a percentage of salary follow the pro rata figure.
• Allowances such as a phone allowance are sometimes paid in full; ask.

After tax, part-time can be worth more than it looks

Because tax is progressive, a lower salary is taxed at a lower average rate. A part-time salary that is 60% of full-time often gives more than 60% of full-time take-home pay. Compare take-home figures for both with the Take-Home Pay Calculator before deciding whether to reduce your hours.

For the proportions themselves, the Percentage Calculator turns hours into a percentage of full time. To convert the result between yearly, monthly and hourly, see hourly to annual salary.