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BMI Calculator

Calculate your Body Mass Index (BMI), identify weight categories, and discover your healthy weight range in metric or imperial units.

Measurement System:
cm
kg
Body Mass Index Score
22.9Normal weight
18.525.030.0
Recommended Healthy Weight Range:

56.7 – 76.3 kg

Note: BMI is a screening metric. It does not directly quantify body fat percentage or lean muscle mass.
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What Is a BMI Calculator?

A Body Mass Index (BMI) calculator estimates body fatness based on an individual's weight and height. Established by Belgian statistician Adolphe Quetelet, BMI is utilized worldwide by the World Health Organization (WHO) and Centers for Disease Control and Prevention (CDC) as an initial health screening metric.

How to Use This Calculator

  1. Select your preferred measurement system (Metric: kilograms and centimeters, or Imperial: pounds, feet, and inches).
  2. Enter your height and weight.
  3. View your computed BMI score, CDC/WHO category classification, healthy weight target range, and BMI Prime.

BMI Formulas

\text{Metric: } \text{BMI} = \frac{\text{weight (kg)}}{[\text{height (m)}]^2} \quad \text{Imperial: } \text{BMI} = \frac{703 \times \text{weight (lbs)}}{[\text{height (in)}]^2}

Divide body weight by height squared. For imperial measurements, multiply weight in pounds by 703 before dividing by height in inches squared.

Worked Example

Scenario: An adult weighs 70 kg and is 175 cm (1.75 m) tall.

Square height in meters: 1.75 × 1.75 = 3.0625 m².

Divide weight by height squared: 70 / 3.0625 = 22.86.

Compare with WHO criteria (18.5 – 24.9 is Normal Weight).

Result: BMI is 22.9, which falls within the Normal Weight range (healthy weight between 56.7 kg and 76.3 kg).

Tips & Key Notes

  • BMI is a population-level screening benchmark, not a diagnostic tool for body fat percentage.
  • Muscular athletes and weightlifters often register higher BMIs despite low body fat due to dense muscle mass.
  • For older adults, maintaining a BMI in the slightly higher range (23–27) is frequently associated with better health outcomes.

Frequently Asked Questions

What are the official BMI categories for adults?

According to the WHO: Underweight (< 18.5), Normal Weight (18.5–24.9), Overweight (25.0–29.9), Obesity Class I (30.0–34.9), Obesity Class II (35.0–39.9), and Obesity Class III (≥ 40.0).

Is BMI accurate for children and teenagers?

For children and adolescents aged 2 to 19, BMI is assessed using age-and-sex-specific growth chart percentiles rather than fixed adult thresholds.

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