If you’ve ever opened the government’s gender pay gap guidance and immediately felt your eyes glaze over, you’re not alone. The official instructions are accurate — but they’re not exactly designed for a Tuesday afternoon. This guide walks you through all six statutory calculations in plain English, in the right order, with worked examples at every step. By the end you’ll know exactly what to calculate, how to calculate it, and where the traps are.
What Are the UK Gender Pay Gap Reporting Requirements?
If your organisation employs 250 or more people in Great Britain, you are legally required to calculate and publish your gender pay gap figures every year under the Equality Act 2010 (Gender Pay Gap Information) Regulations 2017.
There are six statutory figures you must report:
- The percentage of men and women in each hourly pay quarter
- The mean (average) gender pay gap for hourly pay
- The median gender pay gap for hourly pay
- The percentage of men and women receiving bonus pay
- The mean (average) gender pay gap for bonus pay
- The median gender pay gap for bonus pay
You can report figures as whole percentages or rounded to one decimal place — both are compliant.
Before you calculate anything: you need to prepare your data first — identifying which employees to include, working out their ordinary pay, bonus pay, working hours, and hourly pay. If you haven’t done that yet, download our free Data Preparation Checklist before continuing. The calculations only work if the underlying data is right.
Understanding Positive and Negative Figures
Before diving in, it’s worth knowing how to read your results:
- A positive percentage means women have lower pay or bonuses than men
- A negative percentage means men have lower pay or bonuses than women
- A zero means there is no gap between men and women
Most organisations report a positive figure — meaning women are paid less on average than men. A negative figure (sometimes called a reverse pay gap) is less common but equally valid.
Which Employees Do You Include?
This is where a lot of employers go wrong before they’ve even started calculating. There are two different groups of employees, and different calculations use different groups.
Relevant employees are all employees on your snapshot date — full-time, part-time, on leave, job-sharing. You use this group for the bonus pay calculations only.
Full-pay relevant employees are a subset of relevant employees — specifically, those who were paid their usual full pay in the pay period containing your snapshot date. Anyone on reduced pay due to leave (maternity, sick leave, annual leave, and so on) is excluded from this group. You use this group for all other calculations.
Your snapshot date is 5 April for private, voluntary and most public authority employers, and 31 March for most public sector employers.
A Note on Bonuses and Hourly Pay
Before you run any of the hourly pay calculations, there’s an important data preparation step that directly affects your results: bonus pro-ration.
If an employee received a bonus in the snapshot pay period that relates to a longer period — for example, a quarterly or annual bonus — you cannot simply use the full bonus amount when calculating their hourly pay. You must first adjust (pro-rate) it down to the equivalent amount for your pay period.
For example, a £3,600 quarterly bonus paid in a monthly pay period must be pro-rated to approximately £1,200 before being added to that employee’s ordinary pay. Using the full £3,600 would artificially inflate their hourly rate, distorting your quartile and mean figures.
The pro-ration formula is: (bonus ÷ days in the eligibility period) × days in the pay period, using 30.44 days per month and 365.25 days per year.
This applies to the bonus figures used in hourly pay calculations (Step 3a of data preparation) only. The bonus pay gap calculations in steps 4, 5, and 6 use actual bonuses paid over the full 12 months — no pro-ration needed there.
For a full worked example and the complete pro-ration rules, see our dedicated guide: How to Pro-Rata Bonuses for UK Gender Pay Gap Reporting.
Calculation 1: Pay Quartiles
Uses: full-pay relevant employees only
Pay quartiles show the gender split across four equally-sized groups of your workforce, ranked from lowest to highest paid. They’re often the most scrutinised of your six figures because they reveal whether women are concentrated at the lower end of your pay distribution.
How to calculate pay quartiles
Step 1: Sort all full-pay relevant employees from highest to lowest hourly pay.
Step 2: Divide the list into four equal sections. If your headcount isn’t divisible by four, distribute the remainder like this:
- 1 left over → add to the lower quarter
- 2 left over → add one to the lower quarter, one to the upper middle quarter
- 3 left over → add one each to the lower, lower middle, and upper middle quarters
Step 3: Check the gender split at the dividing lines. If employees sharing the same hourly pay rate have been split across two quartiles, redistribute them so the ratio of men to women in each affected quartile reflects the ratio across the whole group sharing that pay rate.
Step 4: For each quartile, calculate the percentage of men and women.
% women in quartile = (number of women ÷ total employees in quartile) × 100
Example: Pay quartile percentages
An employer has 1,112 employees in the lower hourly pay quarter. 187 are men and 925 are women.
Men: 187 ÷ 1,112 × 100 = 16.8%
Women: 925 ÷ 1,112 × 100 = 83.2%
Calculation 2: Mean Gender Pay Gap for Hourly Pay
Uses: full-pay relevant employees only
The mean is the straightforward average — add everything up, divide by the number of people. For the gender pay gap, you calculate a mean hourly rate separately for men and women, then compare them. Remember that each employee’s hourly pay already incorporates any pro-rated bonus from Step 3a of data preparation.
How to calculate the mean hourly pay gap
- Add together the hourly pay of all men. Divide by the number of men. This is the mean hourly pay for men.
- Do the same for women. This is the mean hourly pay for women.
- Subtract the mean hourly pay for women from the mean hourly pay for men.
- Divide the result by the mean hourly pay for men.
- Multiply by 100.
Example: Mean hourly pay gap
1,345 men have a combined hourly pay total of £23,550. Mean male hourly pay: £23,550 ÷ 1,345 = £17.51
3,100 women have a combined hourly pay total of £46,900. Mean female hourly pay: £46,900 ÷ 3,100 = £15.13
Gap: (£17.51 − £15.13) ÷ £17.51 × 100 = 13.59%
This means women are paid 13.59% less than men on average — or 86p for every £1 a man earns.
Calculation 3: Median Gender Pay Gap for Hourly Pay
Uses: full-pay relevant employees only
The median is the middle value when everyone is lined up in order of pay. It’s less influenced by very high or very low earners than the mean, which is why both figures are required — they tell different parts of the story. As with the mean, each employee’s hourly pay already incorporates any pro-rated bonus from Step 3a.
How to calculate the median hourly pay gap
- Sort all men by hourly pay, lowest to highest. Find the man in the middle. His hourly pay is the median hourly pay for men. If there is an even number of men, take the mean (average) of the two middle values.
- Do the same for women to find the median hourly pay for women.
- Subtract the median hourly pay for women from the median hourly pay for men.
- Divide the result by the median hourly pay for men.
- Multiply by 100.
Example: Median hourly pay gap
There are 1,345 men. The middle value is person 673. He earns £15.00/hr.
There are 3,100 women. The two middle values are persons 1,550 and 1,551, earning £13.00 and £15.00. Their mean is £14.00/hr.
Gap: (£15.00 − £14.00) ÷ £15.00 × 100 = 6.67%
This means women are paid 6.67% less than men at the median — or 93p for every £1 a man earns.
Calculation 4: Percentage of Men and Women Receiving Bonus Pay
Uses: all relevant employees (not just full-pay)
This calculation switches to a different employee group. You’re now looking at all relevant employees — including those who were on reduced pay or leave during the snapshot pay period. The question here is simply: what proportion of men and women received a bonus at any point in the 12 months ending on your snapshot date?
How to calculate the bonus receipt percentage
- Count the number of men who received bonus pay in the 12 months ending on your snapshot date. Divide by the total number of relevant men. Multiply by 100. This gives you the percentage of men receiving a bonus.
- Repeat for women.
Example: Bonus receipt percentage
1,375 relevant men — 1,300 received a bonus: 1,300 ÷ 1,375 × 100 = 94.5%
3,125 relevant women — 2,000 received a bonus: 2,000 ÷ 3,125 × 100 = 64.0%
Calculation 5: Mean Gender Pay Gap for Bonus Pay
Uses: all relevant employees (not just full-pay)
This shows the difference in average bonus amounts between men and women. Note that the denominator here is only those who received a bonus — not all relevant employees of that gender. No pro-ration applies here — you use the actual bonus amounts paid over the full 12 months.
How to calculate the mean bonus pay gap
- Add together all bonus payments made to men in the 12 months to your snapshot date. Divide by the number of men who received a bonus. This gives the mean bonus pay for men.
- Do the same for women.
- Subtract the mean bonus pay for women from the mean bonus pay for men.
- Divide the result by the mean bonus pay for men.
- Multiply by 100.
Example: Mean bonus pay gap
Mean male bonus: £1,650. Mean female bonus: £1,490.
Gap: (£1,650 − £1,490) ÷ £1,650 × 100 = 9.7%
Women receive 9.7% less in bonus pay than men on average — 90p for every £1 a man receives.
Calculation 6: Median Gender Pay Gap for Bonus Pay
Uses: all relevant employees (not just full-pay)
Same principle as the median hourly pay gap, but applied to bonuses — and only among those who actually received a bonus. No pro-ration applies — use actual bonus amounts paid over the full 12 months.
How to calculate the median bonus pay gap
- Take all men who received a bonus in the 12 months ending on your snapshot date. Sort them in order of their bonus pay. Find the man in the middle — his bonus is the median bonus pay for men. If there is an even number, average the two middle values.
- Repeat for women.
- Subtract the median bonus for women from the median bonus for men.
- Divide the result by the median bonus for men.
- Multiply by 100.
Example: Median bonus pay gap
Median male bonus: £2,300. Median female bonus: £2,225.
Gap: (£2,300 − £2,225) ÷ £2,300 × 100 = 3.3%
Women receive 3.3% less in bonus pay than men at the median — 97p for every £1 a man receives.
Quick Reference: All Six Calculations
| Calculation | Employee Group | Formula |
|---|---|---|
| 1. Pay quartiles | Full-pay relevant | (Count per gender ÷ quartile total) × 100 |
| 2. Mean hourly pay gap | Full-pay relevant | ((Mean M − Mean F) ÷ Mean M) × 100 |
| 3. Median hourly pay gap | Full-pay relevant | ((Median M − Median F) ÷ Median M) × 100 |
| 4. % receiving bonus | All relevant | (Bonus recipients ÷ total of that gender) × 100 |
| 5. Mean bonus pay gap | All relevant | ((Mean M bonus − Mean F bonus) ÷ Mean M bonus) × 100 |
| 6. Median bonus pay gap | All relevant | ((Median M bonus − Median F bonus) ÷ Median M bonus) × 100 |
The Most Common Calculation Mistakes
Using the wrong employee group for bonus calculations
Calculations 4, 5, and 6 use all relevant employees — including those on leave during the snapshot pay period. Using only full-pay relevant employees for these figures is one of the most common errors, and it understates the total headcount used as the denominator.
Dividing mean bonus pay by all employees instead of bonus recipients
For calculations 5 and 6, the denominator is only the employees who actually received a bonus in the 12 months ending on your snapshot date — not all relevant employees of that gender. Dividing total bonus payments by the full headcount produces a lower mean figure and a distorted gap.
Not pro-rating bonuses before calculating hourly pay
If an employee received a bonus in the snapshot pay period that covers a longer period — such as a quarterly or annual bonus — you must pro-rate it before including it in their hourly pay calculation. Using the full bonus amount inflates that employee’s hourly rate, which skews your quartile distribution and mean hourly pay gap. This is one of the most overlooked steps in the entire process.
Getting the median wrong when there’s an even number of employees
If you have an even number of men or women, there is no single middle person. You take the two employees nearest the middle and average their pay. This is easy to get wrong in a manual spreadsheet, especially for large workforces.
Forgetting to prepare the data properly first
The calculations themselves are straightforward once your data is right. But if you haven’t correctly identified full-pay relevant employees, pro-rated bonuses, or calculated hourly pay — your figures will be wrong before you’ve started. Data preparation is where most errors originate.
Ready to Calculate? Start With Your Data
Every one of the six calculations above depends on clean, correctly prepared data. Before you run any numbers, make sure your employee lists are right, your hourly pay figures are correct, and your bonus data covers the right periods.
📋 Free Download: Data Preparation Checklist
Step through every data decision in the right order — which employees to include, how to handle bonuses, weekly hours, and hourly pay — before you start calculating.
Download Free →Or if you’d rather skip the manual work entirely, the Gender Pay Gap Report Toolkit handles all six calculations in one place. Enter your employee data once and every statutory figure is calculated automatically — including quartiles, medians, and bonus gaps.
⚡ Gender Pay Gap Report Toolkit
Pre-built Excel calculator covering all 6 statutory figures. Enter your payroll data once — the tool handles the rest.
Get the Toolkit →Frequently Asked Questions
How is the gender pay gap calculated in the UK?
There are six statutory calculations: pay quartiles, mean and median hourly pay gaps, the percentage of men and women receiving a bonus, and mean and median bonus pay gaps. The hourly and quartile calculations use full-pay relevant employees only; the bonus calculations use all relevant employees. All gaps are expressed as a percentage of men’s pay.
What is the difference between mean and median gender pay gap?
The mean is the mathematical average — total pay divided by number of employees. The median is the midpoint — the pay of the person in the exact middle of the distribution when everyone is ranked by pay. The median is less affected by a small number of very high earners, which is why both are required. A large difference between the two often signals a small number of very highly paid individuals pulling the mean up.
Does the gender pay gap calculation include part-time employees?
Yes — part-time employees are included, as long as they are full-pay relevant employees (i.e. paid their usual full pay in the snapshot pay period). Because the calculations use hourly pay rather than salary, part-time and full-time employees are treated on a comparable basis.
Are employees on maternity leave included in the gender pay gap calculation?
Employees on maternity leave who received less than their usual pay during the snapshot pay period are excluded from the full-pay relevant employee group — and therefore from calculations 1, 2, and 3. They remain included as relevant employees and are therefore counted in the bonus calculations (4, 5, and 6).
What is a gender wage gap calculation vs a gender pay gap calculation?
In the UK statutory context, the terms are used interchangeably. Both refer to the same six figures required under the Equality Act 2010 (Gender Pay Gap Information) Regulations 2017. The official term used in the legislation and guidance is “gender pay gap.”
Do I calculate the gender pay gap using gross or net pay?
Gross pay — before deductions for tax, National Insurance, and employee pension contributions. However, you use pay after any reduction for a salary sacrifice scheme.