How to Calculate Pay Compression at Work

Learn how to calculate pay compression, identify risk within salary bands and document defensible pay decisions before serious fairness concerns escalate.

A new hire accepts £43,500 for a role where an experienced employee earns £42,000. The offer may have been necessary to secure scarce skills. It may also create a question that HR, Finance and the manager will soon need to answer: why does the person with less organisational knowledge earn more?

Knowing how to calculate pay compression turns that question into evidence. It allows leaders to identify where pay differentials have narrowed, assess whether the position is justified and act before retention, equal-pay or employee-relations concerns become harder to manage.

What pay compression means in practice

Pay compression occurs when the pay difference between employees with materially different experience, responsibility, performance or tenure becomes too small to be meaningful. In some cases, a newer employee may earn the same as, or more than, an established colleague in a comparable role.

Compression is not automatically a pay error. Labour-market conditions can move quickly. A business may need to pay more to recruit a specialist, respond to a minimum-wage increase or retain a critical employee. The concern arises when decisions accumulate without visibility of their effect on the wider pay structure.

For UK employers, the risk is both practical and governance-related. Employees may question whether progression is recognised. Managers may make counter-offers without understanding the implications for their teams. Reward leaders may struggle to explain why people at different points in their career are paid similarly. Where patterns align with sex, ethnicity, age or another protected characteristic, the issue can also warrant closer equal-pay analysis.

How to calculate pay compression

The most useful calculation compares pay for employees who should reasonably have a difference between them. Start with a defined comparator group, such as employees in the same job family, grade, location and working pattern. Then compare new-hire pay with the pay of established employees, or compare employees at different levels of capability within the same salary band.

A straightforward calculation is:

Pay compression gap = New-hire salary - established employee salary

To make the result easier to compare across roles and pay levels, calculate it as a percentage:

Pay compression percentage = (New-hire salary - established employee salary) / established employee salary × 100

Using the example above:

(£43,500 - £42,000) / £42,000 × 100 = 3.6%

The new hire earns 3.6% more than the established employee. That result does not, by itself, establish that action is required. The established employee may have a different scope, lower performance outcomes or a reduced working pattern. But it creates a clear point for review, rather than leaving the discrepancy buried in payroll data.

For a broader view, compare the median salary of recent hires with the median salary of established employees in the same comparator group:

Cohort compression percentage = (Median new-hire salary - median established employee salary) / median established employee salary × 100

Median figures are often more reliable than averages because they reduce the effect of one unusually high offer or long-serving employee. A positive result indicates that recent hires are being paid more than established employees. A result close to zero may show that progression differentials are narrowing.

Measure position within the salary band

Pay compression frequently appears inside salary bands before it becomes obvious in job-level reporting. Calculate each employee's position in range using:

Range position = (Employee salary - band minimum) / (band maximum - band minimum) × 100

If a band runs from £38,000 to £48,000, an employee paid £42,000 sits at 40% through the range:

(£42,000 - £38,000) / (£48,000 - £38,000) × 100 = 40%

Now compare range positions by tenure, performance level, capability or career stage. If a new recruit is at 55% of the range while a well-performing employee with three years' experience is at 40%, the issue is not simply the £1,500 difference. It is the lack of visible reward for experience and contribution within the organisation's own pay framework.

This analysis also reveals band drift. If most new hires enter near the middle or upper half of a band because market rates have risen, the band itself may no longer be fit for purpose. Raising individual salaries without reviewing the range can prolong the problem.

Use comparable pay data, not a single payroll extract

A compression calculation is only as sound as the data beneath it. Comparing annual salaries without normalising working patterns, allowances or job scope can produce misleading results.

Use full-time equivalent base salary as the starting point. Record variable pay, shift premiums, location allowances, retention payments and benefits separately unless they are consistently part of the role's normal cash compensation. A part-time employee's actual salary should not be compared directly with a full-time colleague's annual salary.

Comparator groups also need discipline. Two people may share a job title but perform substantially different work. Conversely, different titles can conceal work of equal value. For initial compression monitoring, group employees by a combination of job architecture, grade, function, location, contracted hours and relevant skill level. For a potential equal-pay concern, a more detailed assessment of job demands and legitimate pay factors may be required.

The aim is not to produce a single organisation-wide compression score. It is to identify credible comparisons that leaders can explain and act upon.

Set thresholds that trigger review

There is no universal percentage at which pay compression becomes unacceptable. A 3% gap may be insignificant in a role with broad performance-related pay. The same gap may be difficult to defend where a longer-serving employee has consistently stronger performance, carries additional responsibilities or is expected to mentor the new hire.

Set review thresholds that reflect your pay philosophy and salary-band design. For example, an employer may review cases where a new hire earns more than an incumbent in the same grade, where employees with materially different career stages are within 5% of one another, or where a new starter enters above a defined range position.

A threshold is a prompt for judgement, not an automatic instruction to increase pay. Each case should consider market evidence, internal equity, performance, scarce skills, geographical factors, previous pay decisions and the employee's current role scope. The discipline lies in applying those factors consistently and recording the rationale.

Investigate the pattern behind the gap

Once a calculation identifies compression, look beyond the individual comparison. Review the employee's pay journey: starting salary, annual increases, promotion dates, market adjustments, retention payments and any changes to job scope. Then consider the same history for the comparator group.

This often reveals the cause. Established employees may have received modest percentage increases during years of low salary movement, while external market rates rose sharply. Or managers may have had discretion to make recruitment offers above the usual entry point without a corresponding process for reviewing incumbents.

The right response depends on the evidence. A targeted adjustment may be appropriate where a specific employee is underpaid against comparable colleagues. A broader market adjustment may be needed where the pattern affects an entire cohort. In other cases, revising salary bands, entry-point rules or promotion criteria will prevent the issue recurring.

Do not treat a counter-offer as the default correction. It can resolve an immediate retention risk while increasing inconsistency elsewhere. If a counter-offer is made, assess its effect on the employee's peer group at the same time.

Document decisions so they can be defended

Pay compression becomes a governance issue when leaders cannot reconstruct how it developed or explain why a particular decision was made. Payroll exports and isolated spreadsheets can show a salary figure. They rarely show the full context: the approved range, market evidence used, comparator analysis, decision-maker, exceptions and follow-up action.

A controlled compensation record should retain the calculation, the comparator group, the data date, the evidence considered and the approved outcome. It should also show whether the decision created a new exception or resolved an existing one. This gives HR, Finance, senior leaders and auditors a shared view of the position without relying on informal recollection.

A platform such as Orgress can bring salary bands, employee pay histories, workforce costs and governance records into one auditable view. That makes it easier to monitor compression continuously, rather than discovering it during a pay review, grievance or board request.

Pay compression is rarely caused by one poor decision. More often, it is the cumulative result of reasonable decisions made without a complete view of their consequences. Calculate it consistently, investigate it proportionately and keep the evidence behind every response. That is how pay decisions remain fair, credible and decisions you can stand behind.