Why Choose Calculations.tools?
Lightning Fast
All calculations happen instantly in your browser. No waiting, no delays.
Accurate Results
Precision-tested algorithms ensure you get the right answer every time.
Mobile Friendly
Fully responsive design works perfectly on phones, tablets, and desktops.
Completely Free
No subscriptions, no hidden fees. All tools are 100% free to use.
Privacy First
All calculations happen locally in your browser. Your data never leaves your device.
Beautiful Design
Modern, clean interface with smooth animations and intuitive controls.
Free Online Calculators for Health, Math & Conversions
Calculations.tools is a free collection of 24 calculators and converters across 5 categories. Every tool runs entirely in your browser — no registration, no data sent to any server, instant results as you type.
Health Calculators
The health section covers BMI, body composition, and fitness metrics. The BMI Calculator adds age and sex context, estimated body fat %, and a healthy weight range. Specialist variants cover men, women, children, teenagers, seniors, and pregnancy. Body composition tools include the Lean Body Mass Calculator (Boer, Hume, James formulas + FFMI), the FFMI Calculator, the Body Fat Calculator (US Navy tape method), and the Ideal Weight Calculator (Devine, Robinson, Miller, Hamwi formulas).
Unit Converters
The conversion section covers the most commonly needed unit types: length (km, miles, feet, inches), weight (kg, lbs, stone, oz), temperature (Celsius, Fahrenheit, Kelvin), height (cm to feet and inches), and a live currency converter covering 150+ currencies with mid-market rates. All converters support bidirectional input and show the full conversion table.
Math & Text Tools
The Percentage Calculator handles all percentage modes: basic percentages, percentage increase and decrease, percentage difference, and percentage of a total — with a formula breakdown for each mode. The Word Counter gives instant word, character, sentence, paragraph, and reading time counts. The Text Diff Checker compares two texts side by side with color-coded additions and removals, and the Excel Diff Checker does the same for spreadsheet files.
Date & Time Tools
The Week Number tool shows the current ISO 8601 week number with a full year calendar and code snippets for 20+ programming languages. The Date Calculator computes the number of days, workdays, weeks, and years-months-days between any two dates, and can add or subtract days from a date.
Frequently Asked Questions
Are all tools really free?
Yes. Every tool on Calculations.tools is completely free — no subscriptions, no usage limits, no premium features. The site is supported by unobtrusive advertising.
Do I need to create an account?
No. All tools are immediately accessible without registration. Visit the tool you need and start calculating.
Are my calculations private?
Yes. All calculations run locally in your web browser. No input data is transmitted to any server.
Do the tools work on mobile?
Yes. Every tool is fully responsive and works on any phone, tablet, or desktop. No app required.
Can I embed these tools on my website?
Several tools offer embeddable widgets — check individual tool pages for the embed option in the sidebar.