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⚖️ BMI Calculator
BMI is a blunt instrument. It was invented in the 1830s by a Belgian statistician for studying populations, not individuals. Every health professional knows it overestimates body fat in muscular people and underestimates it in older adults with low muscle mass. It is still the number your doctor records at every visit, and the one insurance plans use to set premiums, so it is worth knowing yours.
Examples
70 kg, 175 cmBMI 22.9 — Normal weight90 kg, 180 cmBMI 27.8 — Overweight155 lb, 5'9"BMI 22.9 — Normal weightFrequently asked questions
What is a healthy BMI?
WHO classifies 18.5–24.9 as normal weight, under 18.5 as underweight, 25–29.9 as overweight, and 30+ as obese. Asian populations sometimes use slightly lower cutoffs.
Is BMI accurate for athletes?
No. Muscle is denser than fat, so muscular people often score "overweight" by BMI despite low body fat. Body fat % or waist-to-height ratio are better for athletes.
Does BMI work for children?
Children use age- and sex-specific BMI percentile charts, not the adult cutoffs. This calculator is for adults 18 and over.
What is the formula?
BMI = weight (kg) / height² (m²). Or imperial: 703 × weight (lb) / height² (in²).
Should I worry about a BMI slightly above 25?
Probably not by itself. A 25.5 BMI with normal blood pressure, good resting heart rate, and decent fitness is not the same risk profile as 25.5 with high blood pressure and a desk job. The number means more in combination with other markers than alone.
About this tool
BMI Calculator runs entirely in your browser using standard Web APIs. No data is sent to any server. The source for this tool is in our public GitHub repository.
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- 💪 Body Fat Calculator — Estimate body fat % using the US Navy circumference method.
- 🥗 Macro Calculator — Split calorie target into protein, carbs, and fat by goal (cut, bulk, keto).
Why this tool
vs typical free web-tool sites
| 1vw | Typical free site | |
|---|---|---|
| Price | Free | Free |
| Signup required | No | Often (for premium features) |
| Ads inside the tool | No | Yes (banner + video) |
| Data sent to server | No (browser-only) | Yes (inputs analyzed for ads) |
| Total tools | 96 | Often <20 or scattered across sites |
| Bookmarkable URL per tool | Yes | Mixed |
| Loads in under 1s | Yes (static) | Often slow (ad tracking) |
| Multilingual | EN / ES / PT / FR / DE | Usually EN only |
| Open source | Yes | No |