About Calxy

Calxy is a collection of 30 free calculators covering finance, health, mathematics, unit conversion, and everyday questions. Each one is designed to give you a correct answer quickly, and to explain how that answer was reached.

How it works

Every calculation runs entirely in your browser using JavaScript. Nothing you enter is transmitted to a server, logged, or stored. Close the tab and the numbers are gone. This is a deliberate design choice — financial and health inputs are sensitive, and the simplest way to protect them is never to collect them.

Pages are pre-rendered as static HTML, so they load immediately and work without JavaScript for reading the explanations, formulas, and reference tables. Only the interactive calculation requires scripting.

Our approach to accuracy

Where a field has a standard formula, we use it and name it. The calorie calculator uses the Mifflin-St Jeor equation because validation studies favor it over the older Harris-Benedict formula. The body fat calculator uses the US Navy circumference method and states its expected margin of error. Financial calculators use standard amortization and annuity formulas.

Just as importantly, we try to be candid about limits. A BMI figure cannot distinguish muscle from fat. A retirement projection assuming a constant rate of return will not match reality. A due date is an estimate that only about 4% of births land on. Showing a number without its caveats makes it less useful, not more.

What we do not do

• No accounts, sign-ups, or email collection.
• No storing or transmitting the values you enter. The site is supported by advertising, and advertisers never receive anything you type into a calculator.
• No paywalls or usage limits.

Important limitations

These calculators provide general information and estimates. They are not financial, medical, legal, or tax advice, and they cannot account for your particular circumstances. Lenders, clinicians, and tax authorities apply rules and judgments that a general-purpose calculator cannot capture.

For decisions that matter — taking a mortgage, changing your diet, planning your retirement, interpreting a health measurement — treat the output here as a starting point for a conversation with a qualified professional rather than as a conclusion. See our terms of use for the full disclaimer.

Corrections

If you find an error in a calculation or an explanation, we want to know. Every calculator page shows when it was last reviewed, and formulas are documented so results can be independently checked.