About ProRataCalculator

Last updated: February 2026

Our Mission

ProRataCalculator provides free, accurate pro rata salary calculators and employment guides for UK workers. With over 8.7 million part-time workers in the UK (ONS 2024), we believe everyone deserves clear, accessible tools to understand their pay.

Our calculators cover pro rata salary, term-time pay, overtime, day rates, FTE, holiday pay, salary sacrifice, and London weighting — covering the most common employment calculations UK workers need.

Our Methodology

Every calculator on this site follows standard UK employment formulas as used by HR departments, payroll providers, and HMRC:

Pro rata formula: Full-Time Salary × (Actual Hours ÷ Full-Time Hours) — the standard method used by UK employers
Term-time adjustment: Annual Salary × (Term Weeks + Holiday Weeks) ÷ 52.143 — following ACAS guidance for term-time workers
Holiday entitlement: Based on the statutory 5.6 weeks (28 days for full-time) as defined by the Working Time Regulations 1998
Tax calculations: Use HMRC 2025/26 rates — £12,570 personal allowance, 20% basic rate, 40% higher rate
National Insurance: Current 2025/26 employee NI rates from HMRC

Important disclaimer: Our calculators provide estimates for guidance only. They do not constitute financial, tax, or legal advice. Always verify calculations with your employer, HR department, or a qualified professional. Individual circumstances, contractual terms, and employer rounding methods may affect actual pay.

Editorial Standards

All content on ProRataCalculator follows strict editorial standards:

Accuracy: Calculations are verified against official HMRC rates and ACAS guidance
Currency: Content is reviewed and updated at the start of each tax year (April)
Sources: We cite authoritative sources including GOV.UK, ACAS, and ONS
Independence: We are not affiliated with any employer, payroll provider, or government body
Privacy: All calculations run locally in your browser — we never see or store your salary data

About Our Team

ProRataCalculator.uk is built and maintained by a small team of UK-based developers and employment content specialists. Our team has experience in:

UK payroll systems and employment law
HR and people management across education, NHS, and private sectors
Web development and accessibility standards
Financial content writing and fact-checking

We created this site because we saw how confusing pro rata calculations can be — especially for term-time workers, part-time teachers, and people transitioning between full-time and part-time roles. Our goal is to make these calculations simple, transparent, and free for everyone.

Contact Us

We welcome feedback, corrections, and feature requests. Get in touch at or visit our contact page.