What this site is
BMI Fast started as a single-purpose BMI calculator built around one idea: you shouldn't have to create an account, dismiss three pop-ups, and scroll past ads to learn one number about your own body. Every tool here gives you results instantly as you type, works in metric and imperial units, and runs entirely in your browser — your measurements never leave your device.
The tools
- BMI Calculator — Body Mass Index with your category, healthy weight range, and how far you are from it.
- TDEE Calculator — daily calorie needs for maintenance, weight loss, or weight gain.
- Ideal Weight Calculator — four medical formulas plus the BMI-based healthy range.
- Body Fat Calculator — the U.S. Navy tape-measure method, no calipers needed.
Methodology & sources
The formulas behind these tools are standard, published methods: BMI categories follow the World Health Organization and CDC adult cutoffs; calorie needs use the Mifflin-St Jeor equation; ideal weight uses the Devine, Robinson, Miller, and Hamwi formulas; body fat uses the U.S. Navy circumference method with American Council on Exercise categories. Where these methods have known limitations, we say so — see Is BMI accurate?
Medical disclaimer
BMI Fast provides general health information for educational purposes only. It is not medical advice, and the results of these calculators are screening estimates, not diagnoses. Always consult a qualified healthcare provider about your health, weight, diet, or exercise program.
How the site is funded
The site is free and supported by advertising (Google AdSense). We don't sell anything, and we don't collect or sell your data — see our privacy policy for details.