Calculators & tools, that just work.

Websums is a hub of free calculators for the everyday money questions individuals and small business owners actually face — mortgages, take-home pay, self-employment and corporation tax, VAT, retirement timelines, ad spend returns, runway and unit economics. Most online calculators are slow, ad-stuffed, or hidden behind sign-ups; we build fast, focused tools that give you a clear answer and then stay out of the way.

Websums is built and maintained by EllaByte, a UK web studio, which is responsible for the tools and the words around them. We started Websums because we kept needing these calculations ourselves and couldn't find versions that were quick, honest about their assumptions, and free of clutter.

How we keep the tools accurate

Every calculator shows its method and a worked example, so you can see exactly how each figure is reached rather than trusting a black box. Tax rates, thresholds and bands are set to the current UK tax year (2025/26) and checked against primary sources such as GOV.UK and HMRC. When rates change at a Budget or a new tax year begins, we update the affected tools and their accompanying guides. If you spot something that looks off, email hello@websums.com and we'll check and correct it.

Privacy by design

Every calculation happens entirely in your browser — the numbers you type never leave your device and are never sent to us or anyone else. There are no accounts to create and no sign-up walls. The optional "My Sums" feature saves your calculations to your own browser storage only.

Guidance, not financial advice

Websums is designed to help you understand your numbers and plan — it is not regulated financial, tax or investment advice. Figures are estimates based on the inputs and assumptions each tool states, and individual circumstances vary. For major decisions, speak to a qualified adviser, accountant or HMRC. Full details are in our Terms and Privacy Policy.