PoundLogic is a free UK personal finance calculator site. It covers investing, tax, mortgages and borrowing — the four areas where most UK adults make the financial decisions that matter most.
It launched in May 2026 and is built and run by James Taylor.
Why this site exists
UK personal finance is harder than it should be. Tax rules change every April. Mortgage maths is buried inside lender calculators that won't tell you the assumptions. ISA, LISA and pension allowances interact in ways that aren't obvious. And most of the calculators online are either oversimplified, hidden behind a sign-up wall, or built to sell you something at the end.
PoundLogic exists to give you the actual numbers — clearly, without signup, and without pretending to be a financial adviser.
Who runs PoundLogic
PoundLogic is built by James Taylor.
I'm James, the founder of PoundLogic. By day I'm the CTO and co-founder of a SaaS company, a role I've held for nineteen years — so building software that actually works is the part of this site I take most seriously.
PoundLogic exists because I built it for myself first. I've been investing in a Stocks and Shares ISA for the last ten years, I own several buy-to-let properties, and I spend more time than I'd care to admit reading about UK tax, the property market, and the stock market. Every time I wanted to run a calculation — how much my ISA could be worth in twenty years, what the real yield on a buy-to-let actually is after tax, what's the stamp duty on a second property, which mortgage works out cheaper, whether I should put more into my ISA or my pension — I couldn't find a calculator online that did it properly. So I built them and wanted to share them with you.
You can contact me at [email protected] or find PoundLogic on X at @poundlogic.
What PoundLogic is not
PoundLogic is not a regulated financial adviser. The calculators and guides on this site are information and tools, not personal financial advice. If you need advice tailored to your circumstances, speak to a qualified independent financial adviser — you can find one via unbiased.co.uk or VouchedFor.
PoundLogic is not affiliated with HMRC, the FCA, the Bank of England, or any UK government body. Where we use data published by these organisations, we cite the source.
How PoundLogic makes money
PoundLogic is free to use. We make money through affiliate commissions. Some links to financial products — investment platforms, mortgage brokers, and similar services — pay us a commission if you sign up. This never affects the calculator results, never changes the order of recommendations, and is always disclosed on the page.
See our affiliate disclosure for the full detail.
Get in touch
- General questions: [email protected]
- Corrections: [email protected] — if you spot an error, please include the page URL and what you think is wrong
- Location: Portsmouth, United Kingdom