All calculatorsBMI Calculator
Compute your Body Mass Index (BMI), see your weight category, healthy weight range, and a target weight for an ideal BMI, with a gauge and mini chart.
Background
BMI is defined as weight / height², where weight is in kilograms and height in meters. It normalizes body weight for height and is widely used to classify weight status (underweight, healthy, overweight, obesity) in population level health.
How this calculator works
- We convert your height to meters and weight to kilograms (if needed).
- BMI is computed as BMI = weight (kg) / height² (m²).
- Your BMI is compared with common categories: underweight, healthy, overweight, and obesity.
- We also compute a healthy weight range using BMI 18.5 to 24.9 and an "ideal" midpoint target at BMI 22.
Formula and categories
BMI formula: BMI = weight (kg) / height² (m²)
Healthy BMI range: 18.5 to 24.9
Weight range for a given height: weight = BMI × height²
Categories (adult, general guideline):
Underweight: BMI < 18.5
Healthy: 18.5 ≤ BMI < 25
Overweight: 25 ≤ BMI < 30
Obesity: BMI ≥ 30
Example problems and step by step solutions
Example 1 — 170 cm, 65 kg
Height = 1.70 m, weight = 65 kg.
BMI = 65 / (1.70²) = 65 / 2.89 ≈ 22.5 (healthy range).
Healthy weight range (18.5 to 24.9):
18.5 × 2.89 ≈ 53.5 kg and 24.9 × 2.89 ≈ 71.9 kg.
So a weight between about 54 and 72 kg is considered healthy.
Example 2 — 5'6", 180 lb
Height = 5'6" = 66 in ≈ 1.68 m, weight = 180 lb ≈ 81.6 kg.
BMI = 81.6 / (1.68²) = 81.6 / 2.82 ≈ 28.9 (overweight).
Healthy weight range (18.5 to 24.9):
18.5 × 2.82 ≈ 52.2 kg and 24.9 × 2.82 ≈ 70.2 kg.
Target weight for BMI 22: 22 × 2.82 ≈ 62.0 kg (about 137 lb).
Frequently asked questions
Q: How accurate is BMI?
BMI is a simple screening tool. It does not distinguish between muscle and fat or account for all individual differences. It is a good starting point but not a full health assessment.
Q: What BMI is considered healthy?
For most adults, a BMI between 18.5 and 24.9 is considered within the healthy weight range. This is a general guideline and may not apply to every individual.
Q: Why do you show a target BMI of 22?
BMI 22 sits near the middle of the healthy range. Using this value gives a simple reference point for an "ideal" weight while staying within the standard healthy interval.
