Few statistics about work are quoted as often, or argued over as fiercely, as the gender pay gap. It appears in headlines every spring when employers publish their figures, and in conversations about careers all year round. It is also one of the easiest statistics to misread, and the misreading runs in both directions. Some take a gap of 13 per cent to mean that women are paid 13 per cent less than men for the same work. Others take that reading to be false, and conclude that the gap is not real. Neither is right, and the useful answer is somewhere more interesting.
What the national figure measures
The Office for National Statistics publishes the UK’s headline numbers each year. In its 2025 release, the gender pay gap, measured as the difference in median hourly earnings between men and women, was 12.8 per cent among all employees, down from 13.1 per cent the year before. Among full-time employees it was 6.9 per cent, down from 7.1 per cent. Among part-time employees, women’s median hourly pay was slightly higher than men’s, a gap of minus 2.9 per cent.
The important word in all of this is median. The median is the middle value if you line every person up in order of hourly pay. The gap compares the middle man to the middle woman. It is not a comparison of two colleagues doing the same job, and it is not an average of everyone’s pay.
The ONS is explicit on this point. It describes the figure as not a measure of the difference in pay between men and women in the same employment and with similar skills and experience. It is, in the language statisticians use, an unconditional measure: it describes the overall picture, not the explanation.
Why a gap can exist without unequal pay for the same job
If the figure does not measure unequal pay for equal work, what does it measure? The answer lies in who does which jobs, and for how many hours.
The ONS points to several contributing factors. One is working pattern: in April 2025, roughly 84 per cent of men in employment were working full-time, against roughly 60 per cent of women. Because part-time hourly pay tends to be lower, a workforce in which women are more likely to work part-time will show a wider overall gap, even if men and women in any given role were paid identically.
Another is age. The gap is small for younger workers and much larger for older ones: among full-time employees, the ONS reports a gap of 0.9 per cent for the 22 to 29 age group, compared with 12.5 per cent for those aged 50 to 59. That pattern points to what happens over a career, including how time out of the workforce, caring responsibilities and slower progression can add up.
A third is occupation. The ONS reports gaps in favour of men across the major occupational groups, with the largest in skilled trades occupations at 13.9 per cent. Women are also less represented in some of the highest-paying roles, and that matters more as pay rises.
A pay gap is not the same as unequal pay
It helps to separate two ideas that are often run together.
Equal pay is a legal matter. It means that men and women doing the same work, or work of equal value, must receive equal pay. If they do not, that is unlawful, and an individual can challenge it.
The gender pay gap is a statistical measure of difference across a group. It can be large in an organisation that complies perfectly with equal pay law, if, for instance, most of its senior and best-paid roles are held by men and most of its junior roles by women. It can also be small in an organisation that has an equal pay problem hidden in one department.
Neither idea replaces the other. The pay gap is best read as a prompt: it tells you where to look, such as at recruitment, progression, flexible working and who gets the highly paid roles, rather than telling you what is wrong.
How employer reporting works
Since the introduction of mandatory reporting, larger employers have had to publish their own figures. In Great Britain, employers with 250 or more employees must report annually. The reference date, known as the snapshot date, is 31 March for the public sector and 5 April for private and voluntary-sector employers, and the figures must be published within a year of it.
The required disclosures go beyond a single headline. Employers publish their mean and median gender pay gaps, the gap in bonus pay, the proportion of men and women who received a bonus, and the proportion of men and women in each pay quartile. The last of these is the most revealing for many readers, because it shows where women and men sit in the pay structure, and not just the average.
A useful habit when you see a company’s figures is to look at the quartiles first. A company whose gap is mostly explained by women making up most of the lowest-paid quartile and few of the highest is telling a different story from one with an even spread and a gap that comes from somewhere else.
Reading the headline without being fooled by it
A few questions make any pay-gap figure easier to interpret.
- Mean or median? They can be very different, because a handful of very high earners moves the mean.
- All employees or full-time? The full-time gap is much smaller than the overall one, for the reasons above.
- Same organisation or whole economy? A national figure tells you about the labour market; an employer’s figure tells you about that employer.
- What changed? The year-on-year change is often smaller than the headline suggests, and the national gap has narrowed slowly.
What the number is for
The gender pay gap is a blunt instrument, and its defenders and critics would probably agree on that. Its strength is that it is simple and comparable, and that it makes an employer’s pay structure visible in a way that would otherwise be hard to see. Its weakness is that it can be read as an accusation or as an excuse, when it is really a description. It is most useful for what it asks: who gets the better-paid roles, who works the hours that are paid best, and what would have to change for the picture to look different.
This article is general information based on official statistics and published guidance. It is not legal advice; for questions about your own pay, speak to your employer, a trade union or Acas.
Sources: Office for National Statistics (Gender pay gap in the UK: 2025); GOV.UK (Gender pay gap reporting: guidance for employers)
