About this BMI Calculator
BMI is one of the most widely used health metrics globally. While not perfect, it provides a quick snapshot of whether a person's weight is appropriate for their height. It is used by doctors and insurers to screen for weight categories that may lead to health problems.
Who this calculator is for
- Adults who want a quick weight-for-height screening number.
- People comparing current weight status against standard BMI categories.
- Anyone deciding whether to explore other body-composition tools next.
When to use it
- Use this calculator for a fast first-pass weight screening.
- Use it when tracking broad changes after weight loss or weight gain.
- Use it alongside body-fat or waist-based tools for more context.
How to use this calculator
- Select your Unit System (Metric or Imperial).
- Enter your Height in feet/inches or centimeters.
- Enter your Weight in pounds or kilograms.
- Review your BMI Score and corresponding Category.
Key assumptions
- BMI assumes weight relative to height is a useful screening proxy for health risk in the general adult population.
- The result uses standard adult BMI cutoffs rather than athlete-specific, child-specific, or pregnancy-specific guidance.
- BMI does not separate fat mass from muscle mass or show where weight is carried.
Accuracy and testing
Review formula sources, default test cases, assumptions, unit handling, rounding rules, and changelog for this calculator.
How this calculator works
Inputs explained
Height
Your standing height without shoes.
Weight
Your current body weight. For the most accurate result, weigh yourself in the morning before eating.
Understanding your results
Example scenarios
Normal Range
Height 5'10" (70 inches), Weight 160 lbs. BMI = 23.0. This falls within the healthy range.
Overweight Range
Height 5'4" (64 inches), Weight 170 lbs. BMI = 29.2. This indicates the person is overweight.
Key Features
- Standard CDC Categories
- Metric & Imperial Support
- Instant Classification
Things to Keep in Mind
BMI does not distinguish between muscle mass and fat mass. It implies that a high weight-to-height ratio is due to fat, which isn't always true for athletes.
Tips & Best Practices
- Muscle weighs more than fat. If you are a bodybuilder or athlete, BMI may classify you as overweight even if you have low body fat.
- Waist circumference is often a better predictor of health risks than BMI alone.
- Older adults (65+) may benefit from having a slightly higher BMI (25-27) to protect against frailty.
Glossary of Terms
- BMI
- Body Mass Index. A simple index of weight-for-height used to classify underweight, overweight, and obesity.
- Obesity
- A complex disease involving an excessive amount of body fat, defined by a BMI of 30 or higher.