About Calculators

Free, fast calculators for loans, investing, salary, health, dates and conversions.

Free online calculators with instant results: loan and mortgage payments, compound interest, retirement, take-home pay, BMI, calorie needs, dates and unit conversions.

How pages are built

Each calculator is a single HTML page. The formula is implemented once in JavaScript for the live result and once in Python for the server-rendered answer shown before scripts run; an automated check runs both implementations against the same inputs and fails the build if they disagree. Pages state their assumptions, show a worked example and list common mistakes.

Not professional advice

Financial, tax and health results are estimates for planning. Consult a qualified professional before making decisions with legal, tax or medical consequences.

This site is run by an automated publishing system. Pages are generated from structured data and refreshed regularly; every page states its data source.

Data & corrections

Every calculator shows its formula, a worked example and common mistakes. Results are estimates — verify anything financial or medical with a qualified professional. If you spot an error, contact us and it will be corrected in the next data refresh.