Body Mass Index with WHO classification, healthy weight range, and an interactive scale — 100% private.
BMI is a screening measure, not a diagnosis. It does not account for muscle mass, bone density, age, sex, or body-fat distribution. Talk to a healthcare professional before making any weight-management decisions.
Your BMI sits on this scale. The green zone (18.5–24.9) is the reference 'normal' range; the inset rounded marks show common BMI points for reference.
In metric units: divide weight in kilograms by the square of height in meters. The category thresholds are fixed by the WHO regardless of age or sex.
| BMI range | Category | Health risk |
|---|---|---|
| < 18.5 | Underweight | Increased (nutritional deficiency) |
| 18.5 – 24.9 | Normal weight | Lowest |
| 25.0 – 29.9 | Overweight | Moderate |
| 30.0 – 34.9 | Obesity (Class I) | High |
| 35.0 – 39.9 | Obesity (Class II) | Very high |
| ≥ 40.0 | Obesity (Class III) | Extremely high |
Ranges per WHO. Asian-Pacific guidelines use lower cut-offs (23 / 27.5) for elevated risk — check what applies to you.
Mia is 175 cm and weighs 74 kg. Let's compute her BMI and healthy range.
Free BMI calculator with WHO classification, healthy weight range for your height, and an interactive scale. Everything runs locally; nothing is uploaded.
FreeToolHub BMI Calculator is a free browser-based tool — free BMI calculator with WHO classification, healthy weight range for your height, and an interactive scale. No signup, no upload; everything runs locally in your browser.
Free BMI calculator with WHO classification, healthy weight range for your height, and an interactive scale. Metric (kg/cm) and imperial (lb/ft-in) support. 100% private, runs in your browser.
This calculator computes your Body Mass Index (BMI) — your weight relative to your height — and places it on the WHO's five-category scale from underweight to class III obesity. Alongside the index number it returns two numbers that matter more in practice: the healthy weight range for your exact height, and how many kilograms (or pounds) you are above or below that range. The interactive scale positions your result visually, so the category and your distance from a healthy range are clear at a glance. Metric and imperial inputs are both supported. Everything runs in your browser — no weight or height data ever leaves your device.
(1) Enter your weight and height in either metric (kg, cm) or imperial (lb, ft/in) units. (2) The tool computes BMI as weight ÷ height² and classifies it per WHO thresholds. (3) It derives the healthy weight range for your height (18.5–24.9 × height²) and tells you exactly how much to lose to reach the top of the range or gain to reach the bottom. (4) The scale above the results positions your number among the categories. Because muscle raises BMI without raising health risk, treat the figure as a screening signal and pair it with other measures when making decisions.
BMI is best read as two useful bookends rather than one verdict. On the useful side: the healthy weight range scales precisely to your height, so the distance you sit from that range — in either direction — is actionable, and population studies consistently link BMIs outside 18.5–24.9 with higher risks of cardiovascular disease, type 2 diabetes, and joint problems. On the limits side: BMI cannot distinguish muscle from fat, does not capture where fat sits (visceral fat around the organs matters more than hip and thigh fat), and shifts meaning at the extremes of height. That is why practitioners pair it with waist circumference (under 40 in / 102 cm for men, 35 in / 88 cm for women flags risk) and, when body-fat % is known, formulas like Katch-McArdle that see lean mass directly. A practical way to use this tool: recheck after any sustained diet or training change and watch the trend of your distance from the healthy range, not the daily number.
The WHO classifies 18.5 to 24.9 as normal weight. Under 18.5 is underweight, 25.0–29.9 is overweight, and 30.0+ is obesity (subdivided into classes I–III at 35 and 40).
Body mass index ignores body composition, so muscular people can read as overweight or obese despite low body fat. It is a screening measure for populations, not a diagnosis for individuals.
Divide your weight in kilograms by the square of your height in meters. For example, 74 kg ÷ (1.75 m)² = 24.2. This calculator does the math and classifies the result for you.
The adult BMI formula and WHO thresholds are identical for men and women. Composition differences mean the same BMI can carry different health risk between the sexes — waist measurement adds that context, which BMI alone cannot.
No. Children need age-and-sex percentile charts (BMI-for-age), and pregnancy weight gain follows separate Institute of Medicine ranges by pre-pregnancy BMI. Use this calculator only for non-pregnant adults 18+.
This tool is also known by these tasks — each link opens the same tool with a focused guide:
What do you call a nosy pepper?
No signups, no data sold. Every tool is free to use — the free tier allows 5 downloads or saves per day, and the optional Pro plan ($7/mo, $59/yr) adds unlimited downloads, batch processing, white-label exports and an ad-free experience.
☕Support me on Ko-fi— support the free tier100% of proceeds go towards hosting & building more free tools.