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Summary
A pro-rata salary is the proportional pay a part-time worker receives based on their hours relative to a full-time equivalent (FTE). If a full-time role pays £40,000 for 37.5 hours per week and you work 22.5 hours, your pro-rata salary is £24,000. The calculator converts between FTE and actual salary and shows the resulting take-home pay after UK tax deductions.
How it works
The formula
Pro-rata salary = FTE salary x (Actual hours / FTE hours)
This scales the full-time salary linearly by the fraction of full-time hours worked. The same formula applies to other pro-rated benefits like holiday entitlement and pension contributions.
Holiday entitlement
Part-time workers receive the same proportional holiday as full-time staff. The UK statutory minimum is 5.6 weeks regardless of hours, but the number of days depends on your working pattern:
- Full-time (5 days/week): 28 days
- Part-time (3 days/week): 16.8 days
- Part-time (4 days/week): 22.4 days
Tax implications
A pro-rata salary below the personal allowance (£12,570) means no income tax is due. Even above the allowance, part-time workers benefit from the same tax-free amount as full-time workers, so the effective tax rate is often lower.
Worked example
FTE salary: £45,000 at 37.5 hours/week, working 3 days (22.5 hours)
- FTE fraction: 22.5 / 37.5 = 0.6 (60%)
- Pro-rata salary: £45,000 x 0.6 = £27,000
- Income tax: (£27,000 - £12,570) x 20% = £2,886
- Employee NI: (£27,000 - £12,570) x 8% = £1,154
- Net pay: £27,000 - £2,886 - £1,154 = £22,960
- Monthly take-home: £1,913
- Pro-rata holiday: 28 x 0.6 = 16.8 days
Compare: the full-time equivalent net pay would be approximately £34,471. Working 60% of the hours gives about 66.6% of the net pay, because the lower salary attracts proportionally less tax.
Inputs explained
- FTE salary — the full-time equivalent annual salary (what the role would pay for full-time hours)
- FTE hours per week — standard full-time hours for the role (typically 37.5 or 40)
- Actual hours per week — your contracted part-time hours
- Days per week — for calculating pro-rata holiday entitlement
Outputs explained
- Pro-rata gross salary — your actual annual salary before deductions
- FTE fraction — the percentage of full-time hours you work
- Take-home pay — net salary after tax, NI, and other deductions
- Pro-rata holiday — your statutory holiday entitlement in days
- Hourly rate — gross and net pay per hour
Assumptions & limitations
- Assumes a linear scaling of salary by hours. Some employers pay different hourly rates for different hour bands or offer premium rates.
- Tax-free personal allowance is applied in full regardless of hours worked — it is not pro-rated.
- Does not account for compressed hours (e.g., full-time hours in fewer days) which would give 100% pay, not pro-rata.
- The Part-time Workers (Prevention of Less Favourable Treatment) Regulations 2000 protect part-time workers from less favourable treatment in pay rates, but pro-rata reduction itself is lawful.