About ProRata Calculate — Why This Site Exists

What the site does

This is a small, single-purpose website. It takes the full-time figures an employer, landlord or provider starts from, applies your proportion — your hours, your days, your weeks, your dates — and shows the resulting amount together with the whole of the arithmetic that produced it. Alongside the calculators sit plain-English guides: what the phrase means, how the calculation is done by hand, how leave entitlement is built, and how to check adverts and payslips for the errors that recur often enough to deserve names. That is the complete offering. There are no accounts, no subscriptions, no premium tier and nothing to download.

How the figures are produced

Every calculation runs locally, in your browser, the moment you type. Nothing you enter is transmitted to a server, stored in a database or seen by anyone — the site has no server-side processing at all, a design chosen deliberately: pay figures are personal, and a calculator that never receives them can never leak, sell or mishandle them. The tax and National Insurance estimates use the published rates for the UK tax year 2026/27, including the Scottish income tax bands published by the Scottish Government, and the pages state the rates used and the date they were last reviewed. Holiday calculations follow the rules summarised by GOV.UK and Acas, including the 12.07% accrual method for irregular-hours and part-year workers in leave years from 1 April 2024.

What the site is not

It is not financial, tax, legal or employment advice, and it is not a substitute for your contract, your payslip or HMRC’s own calculators. Pro rata outcomes depend on the exact wording of individual contracts — particularly for term-time weeks, bank holiday treatment and pension bases — and where a figure on this site and a figure from your employer differ, the right next step is the written query described in our guides, not an assumption that either side is automatically correct. Where the site’s estimates end, GOV.UK, Acas and Citizens Advice are the authoritative places to continue, and the guides link to them in spirit throughout.

Corrections and contact

Ratings, thresholds and rules change — usually each April — and pages are reviewed when they do. If you spot a figure that looks out of date, an example that does not reconcile, or wording that confused you at exactly the moment you needed clarity, please write to [email protected] and say which page and which figure you were looking at. Corrections from readers checking real payslips are the most valuable quality control a site like this can have, and they are acted on. The same address reaches us for everything else the site covers; for anything personal — your own tax position, a dispute with an employer — please use the free official services named above, which can see your full circumstances and this site cannot and should not.

Finally, a word about the design you are looking at. It is deliberately plain: large type, honest tables, no invented statistics, no testimonials, no stock photographs of smiling offices. A site whose entire argument is “show your working” should look like it has nothing to hide. We think this one does — and if you find the place where it does not, the email address is in the paragraph above.