BMI Calculator

Overview

This BMI calculator finds your Body Mass Index from your height and weight. BMI is a simple screening measure used to categorize weight ranges that may be linked to health risk.

How to Use This Tool

1. Choose the unit system. You can select Imperial (feet/inches, pounds) or Metric (centimeters, kilograms).
2. If you pick Imperial, enter your height in feet and inches and your weight in pounds.
3. If you pick Metric, enter your height in centimeters and your weight in kilograms.
4. Click the Calculate BMI button to get your result.

How the Calculation Works

BMI = weight (kg) ÷ height (m)². When using pounds and inches, weight is converted to kilograms and height to meters before the same formula is applied. For example, someone who is 5'8" (173 cm, or 1.73 m) and weighs 160 lbs (72.6 kg) has a BMI of 72.6 ÷ 1.73² = 72.6 ÷ 2.99 ≈ 24.3, which falls in the Normal weight range.

Interpreting the Results

The tool shows your BMI number and classifies it as Underweight, Normal weight, Overweight, or Obese using the standard adult BMI ranges. These are the same thresholds used by the WHO and CDC for adult screening.

Limitations and Special Notes

BMI is a screening tool, not a diagnosis. It does not account for muscle mass, bone density, or body composition directly, so it can be misleading for athletes, older adults, or people with high muscle mass. This calculator is designed for adults age 20 and over — for children and teens, use the BMI percentile calculator instead, since growing bodies are measured against age- and sex-specific percentile charts rather than fixed adult categories. This tool is not medical advice and does not replace a doctor's assessment of your health.

Common Use Cases

Use this calculator for a quick general health screening check, to track weight changes over time, or as a starting point before talking to a healthcare provider about a healthy weight range.