Body Mass Index with healthy-weight range and waist-to-height ratio. Free, private, runs in your browser.
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BMI
22.9
Normal
Healthy range for your height: 56.7–76.3 kg
WHtR is a complementary health indicator. Rule of thumb: keep waist under half your height.
Educational only. Not medical advice. BMI does not distinguish muscle from fat and does not apply to under-18s, pregnancy, or elite athletes.
Body Mass Index is a simple ratio — weight divided by height squared — that places you on a scale the World Health Organization standardised for adults. The category boundaries are 18.5 (underweight / normal), 25 (normal / overweight), 30 (overweight / obese), 35 (Obese I / II), and 40 (Obese II / III). For most adults, a BMI in the normal range correlates loosely with lower cardiovascular-disease and type-2-diabetes risk at the population level, which is why doctors use it as a quick screening indicator.
BMI doesn't distinguish muscle from fat. A heavily-muscled athlete can register as 'overweight' or 'obese' while carrying very little body fat, and conversely a sedentary person with low muscle mass can have a 'normal' BMI while carrying unhealthy visceral fat. BMI also doesn't apply to under-18s (use paediatric BMI-for-age percentiles), pregnancy, or people with skeletal differences. It's useful as a screen, never as a diagnosis — your doctor will look at BMI alongside waist circumference, blood pressure, blood glucose, lipids, and activity level.
WHtR is a complementary indicator that correlates with visceral fat — the metabolically active fat around your organs — better than BMI does. The simple rule: keep your waist circumference under half your height. In numbers, a WHtR under 0.5 is generally healthy, 0.5–0.6 indicates increased health risk, and above 0.6 is high risk. Because it accounts for where fat sits (abdominal fat is riskier than hip or limb fat), WHtR is increasingly used alongside BMI in research and in some clinical guidelines.
The tool back-calculates the weight range that would land you in the 18.5–24.9 BMI band for your specific height. This is a reference, not a target — plenty of healthy people sit outside this range. Use it as a sanity check: if your weight is far below or above the range, it's worth discussing with a doctor who can assess the full picture (body composition, activity, family history, metabolic markers).
Weight and height are private. This tool performs all calculations locally in your browser — nothing is sent to any server, logged, or stored beyond the current page session. No account, no tracking of individual values.
WHO defines 18.5–24.9 as the normal range for adults. Below 18.5 is underweight; 25–29.9 is overweight; 30+ is obese, further split into Obese I (30–34.9), II (35–39.9), and III (40+). These categories do not apply to under-18s, pregnant people, or elite athletes with unusually high muscle mass.
BMI is a blunt screening tool — it doesn't distinguish fat from muscle, and it can misclassify heavily-muscled or unusually tall people. It's useful as a rough health indicator at the population level and as a starting point, but it isn't a diagnostic test. Waist-to-height ratio (shown on this page) is a better individual indicator of visceral-fat risk.
WHtR measures how much of your height your waist circumference is, and correlates with visceral fat better than BMI. The rule of thumb is 'keep your waist under half your height' — a ratio under 0.5 is generally healthy. Ratios above 0.6 are associated with higher health risk.