Financial decisions shouldn’t require a finance degree. We build free tools that show you the numbers — and explain them.
financestool is a free financial tools platform. We build interactive calculators for mortgages, loans, savings, retirement, investing, taxes and business finance — each one paired with the underlying formula, a worked example and plain-English explanations, so you understand why the number is what it is, not just what it is.
Alongside the calculators, we publish downloadable Excel templates with working formulas, a plain-English financial glossary, and educational guides.
Every calculator uses the standard formulas employed by banks, lenders and financial planners — the amortization formula, compound interest mathematics, CAGR and so on — and each page shows the formula openly so you can verify the math yourself. Calculations run instantly in your browser: the numbers you enter are never sent to or stored on our servers.
Free and open. Every tool works without an account, a paywall or a sign-up form.
Show the math. A result you can’t verify is a result you shouldn’t trust. Every calculator page includes its formula and a worked example.
Education, not advice. We explain concepts and compute estimates; we don’t tell you what to buy or sell. For decisions with real stakes, we consistently recommend consulting a qualified professional.
Questions, corrections or suggestions? We genuinely want to hear them — reach us through the contact page.