BMI Calculator
Calculate your Body Mass Index (BMI) and see which weight category you fall into.
About This Tool
The BMI Calculator computes your Body Mass Index from height and weight in either metric (kg, cm) or imperial (lb, ft/in) units. BMI is a widely used screening measure that categorizes weight into four ranges: Underweight (<18.5), Normal weight (18.5–24.9), Overweight (25–29.9), and Obese (≥30).
BMI = weight (kg) ÷ height² (m). Note that BMI does not directly measure body fat percentage and may be less accurate for athletes (higher muscle mass), elderly individuals, or growing children. It is a screening tool, not a medical diagnosis — consult a healthcare provider for a complete health assessment.
How to Use
- Select your unit system: Metric (kg, cm) or Imperial (lb, ft + in).
- Enter your weight in the weight field.
- Enter your height in the height field (for imperial, fill both feet and inches).
- Click Calculate BMI to see your BMI value and weight category.
Use Cases
Healthcare professionals use BMI as a quick population-level screening metric for weight-related health risks. Individuals use it to track weight changes over time relative to their height. Fitness programs use BMI alongside body composition measurements to set initial baseline goals. Insurance applications and clinical intake forms often request BMI as a standard health indicator.
FAQ
- What is a healthy BMI range? — A BMI of 18.5–24.9 is classified as Normal weight according to WHO guidelines.
- Is BMI accurate for athletes? — Not always. Muscle is denser than fat, so athletes with high muscle mass may have a high BMI despite low body fat.
- Does BMI differ by age or gender? — The standard BMI formula applies to adults. For children and teens, age- and gender-adjusted BMI percentiles are used.
- What is the BMI formula? — BMI = weight (kg) ÷ height² (m²). For imperial: BMI = 703 × weight (lb) ÷ height² (in²).