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BMI Calculator

Calculate your Body Mass Index and see which weight category you fall into.

Your details

Results

Your BMI
22.9
Normal weight · BMI prime 0.91
Healthy weight range
56.7 kg – 76.3 kg
BMI 18.5 – 24.9 for your height
Weight to lose / gain to reach normal
Already in healthy range
BMI scale
15 – 40
1518.5253040
Underweight
Normal
Overweight
Obese

What is the BMI Calculator?

A BMI calculator is a free online tool that calculates your Body Mass Index (BMI) from your height and weight. BMI is a widely used screening metric that classifies adults as underweight, normal weight, overweight, or obese.

BMI Calculator formula

BMI = weight (kg) ÷ height (m)². In imperial units: BMI = 703 × weight (lb) ÷ height (in)². Standard adult categories: underweight < 18.5, normal weight 18.5–24.9, overweight 25–29.9, obese 30+.

How to use the BMI calculator

  1. 1Choose your preferred units — metric (kg, cm) or imperial (lb, in).
  2. 2Enter your height in the height field.
  3. 3Enter your current body weight.
  4. 4Click Calculate to see your BMI value and the category it falls into.
  5. 5Use the BMI chart to compare your result to the healthy range for your height.

Example calculation

For an adult who is 70 kg and 175 cm tall: BMI = 70 ÷ (1.75 × 1.75) = 70 ÷ 3.0625 = 22.9, which falls in the Normal weight range (18.5–24.9).

Frequently asked questions

What is a healthy BMI?
A healthy BMI for most adults is between 18.5 and 24.9. Below 18.5 is considered underweight, 25–29.9 is overweight, and 30 or higher falls in the obese range.
How accurate is the BMI calculator?
BMI is a quick screening tool that works for most adults, but it does not directly measure body fat. Very muscular athletes may register as overweight despite low fat, and older adults can have a normal BMI but high body fat. BMI is a screening metric, not a diagnostic of body fatness or health — consult a doctor for personal advice.
Does BMI work for children and teens?
For children and teens aged 2–19, BMI is plotted on age- and sex-specific CDC growth charts and reported as a percentile rather than a fixed category.
What BMI should a 5'9" man aim for?
For an adult who is 5'9" (175 cm), a weight between roughly 125–168 lb (56.7–76.2 kg) places BMI in the 18.5–24.9 normal range.

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