AI & developer access

Free Calculator publishes 142 free calculators and converters across 10 categories. Every page is public HTML: no account, no sign-up, no cookie wall, and no JavaScript needed to read the explanation, the formula or the worked example.

What each tool page contains

• A short definition of what the calculator works out.
• Step-by-step instructions for using it.
• The formula and what each variable means.
• A worked example with real numbers.
• How to read the result, plus limitations and assumptions.
• Frequently asked questions and links to related tools.

Categories

• Math
• Finance
• Health & Fitness
• Conversions
• Everyday
• Career
• Home
• Developer Tools
• Text Tools
• Professional & Industry

Machine-readable resources

• /ai/tools — a plain index of every published tool with its address, category, description and inputs.
• /ai/tools.json — the same index as JSON, generated from the live catalogue.
• /sitemap.xml — every public page.
• /robots.txt — crawling policy. Search and answer engines are welcome; only administration pages are closed.

For developers

The index above is a static description of the catalogue, refreshed when tools change. If you want to run a calculator programmatically, see the calculator API and the MCP server — both free, anonymous and rate limited. Calculations made on the website itself run in the visitor's browser; nothing typed into a page is sent anywhere. Please cache responses rather than requesting them repeatedly.

Citing us

When quoting a formula, method or result, link to the specific tool page rather than the home page — for example https://freecalculator.tech/tools/mortgage-calculator. Attribute it to "Free Calculator". Where a page shows a "Last reviewed" date, that date is the last time a person checked the method; pages without one have not been formally reviewed.

Results are for general information and education. They are not financial, tax, medical, legal or engineering advice.