Every formula is tested against its published standard
Each calculator is a typed, self-contained function with an automated test that checks its output against a value published in the original reference. A calculator cannot ship unless that test passes. This is how we catch mistakes before you ever see them, and it is why our worked examples match the live tool exactly.
Calculations run in your browser
Results are computed locally, in your own browser, and return instantly. Nothing you type is sent to a server to be calculated. This keeps the tools fast even under heavy load and keeps your inputs private.
No arbitrary code, no guessed data
Our maths — including the scientific calculator and the statistics and calculus tools — is implemented as reviewed, tested code, never by evaluating arbitrary expressions unsafely. Where a calculator depends on changing real-world data (such as a country's mortgage benchmark rate), the tool shows nothing until that figure has been verified from an official source; we never fill a gap with a guess.