About

Last updated: 9 October 2026

Plain Sums is a small set of free UK calculators and paid spreadsheet templates, made by Arthur Jones in the UK. It started with calculators for construction trades on the Construction Industry Scheme, then grew to cover probate, gifts, late payment and the VAT threshold.

How the calculators work

Each calculator runs in your browser and links to the GOV.UK, HMRC or Bank of England pages it is based on, with the date the rates were last checked. Nothing you type is sent anywhere. They give estimates, not tax, legal or financial advice. See the disclaimer.

The templates

The spreadsheet templates are sold on Gumroad, which handles payment and delivery. The calculators stay free either way.

Contact

Message me through my Gumroad profile, which has a message option. Bug reports, corrections and questions are all welcome. Replies can take a few days.