BMI Calculator
By Miikka · CalcBrew · Updated
Body Mass Index (BMI) is the ratio of weight to height that gives a rough estimate of whether your weight is in a healthy range. BMI is calculated as weight (kg) / height (m)².
How the calculator works and what it’s for▾
BMI categories
Under 18.5 = underweight, 18.5–24.9 = normal, 25–29.9 = overweight, 30 or over = obesity. These apply to adults (18+); children use age- and sex-specific charts.
What BMI doesn’t tell you
BMI doesn’t distinguish muscle from fat or account for where fat sits. A muscular person can have an "overweight" BMI with low body fat. Also look at waist circumference and body fat percentage.
Example
A person 175 cm tall weighing 75 kg: BMI = 75 / 1.75² ≈ 24.5 → normal. The healthy weight range for 175 cm is about 57–76 kg.
Tips
Use BMI as a guide, not the only measure. Waist circumference (over 100 cm for men, 90 cm for women) indicates abdominal fat, which is riskier. Consult a doctor if unsure.
🔄 Reviewed June 2026
BMI formula in US and metric units
Worked example: 5 ft 9 in is 69 inches, so a 170 lb adult has a BMI of 703 × 170 ÷ 69² = 119,510 ÷ 4,761 = 25.1, just inside the overweight range. In metric the same person is 175 cm and 77 kg: 77 ÷ 1.75² = 25.1. Use the US/Metric switch on the calculator to enter either set of units.
Adult BMI categories (CDC and WHO)
| BMI | Category | Weight at 5 ft 6 in |
|---|---|---|
| below 18.5 | Underweight | under 115 lb |
| 18.5–24.9 | Healthy weight | 115–154 lb |
| 25.0–29.9 | Overweight | 155–185 lb |
| 30.0–34.9 | Obesity, class 1 | 186–216 lb |
| 35.0–39.9 | Obesity, class 2 | 217–247 lb |
| 40 and above | Obesity, class 3 | 248 lb and up |
The CDC in the United States and the WHO worldwide use the same cut-offs for adults aged 20 and over. For people of Asian descent many clinicians act earlier, at 23 for overweight and 27.5 for obesity, because health risks rise at a lower BMI. Children and teens aged 2 to 19 are assessed as a BMI-for-age percentile on the CDC growth charts, not with these adult ranges.
Healthy weight range by height
The weight that gives a BMI of 18.5 to 24.9 at each height, rounded to the nearest pound and kilogram.
| Height | Healthy weight (lb) | Healthy weight (kg) |
|---|---|---|
| 4 ft 10 in (147 cm) | 89–119 lb | 40–54 kg |
| 5 ft 0 in (152 cm) | 95–128 lb | 43–58 kg |
| 5 ft 2 in (157 cm) | 101–136 lb | 46–62 kg |
| 5 ft 4 in (163 cm) | 108–145 lb | 49–66 kg |
| 5 ft 6 in (168 cm) | 115–154 lb | 52–70 kg |
| 5 ft 8 in (173 cm) | 122–164 lb | 55–74 kg |
| 5 ft 10 in (178 cm) | 129–174 lb | 59–79 kg |
| 6 ft 0 in (183 cm) | 136–184 lb | 62–83 kg |
| 6 ft 2 in (188 cm) | 144–194 lb | 65–88 kg |
| 6 ft 4 in (193 cm) | 152–205 lb | 69–93 kg |
Age, sex, muscle: what BMI does not tell you
BMI compares weight with height and nothing else. It cannot tell muscle from fat, so a 5 ft 10 in, 200 lb athlete scores 28.7 and is labeled overweight while carrying little body fat. It does not adjust for sex, although women naturally carry more body fat than men at the same BMI, and it does not adjust for age, although adults tend to lose muscle after 50, so the same BMI at 70 usually means more fat than it did at 30. Fat distribution matters too: weight around the waist raises risk more than weight on the hips.
For a fuller picture, measure your waist (over 40 in for men or 35 in for women signals higher risk at any BMI), estimate your body fat percentage, and compare your ideal weight from several formulas. If you plan to change your weight, the calorie calculator turns the target into a daily intake.
Frequently asked questions
Cite this calculator
CalcBrew. (2026). BMI Calculator. https://calcbrew.com/bmi-calculator“BMI Calculator.” CalcBrew, 2026, calcbrew.com/bmi-calculator.Link to https://calcbrew.com/bmi-calculator. Results are estimates; cite the underlying formula or data source for academic work.
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