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Home› Health Calculators› Body & Fitness› BMI Calculator

BMI Calculator
with Body Mass Index & Healthy Weight Range

Calculate your BMI using metric or imperial units, see your category band, and estimate a general healthy weight range for your height.

⚖️
BMI Calculator
Metric inputs
kg
Enter body weight in kilograms.
cm
Enter height in centimetres.
Imperial inputs
lb
Enter body weight in pounds.
ft
Feet part of height.
in
Inches part of height.
BMI Result
—
body mass index estimate
BMI Score
—
calculated body mass index
Category
—
general BMI classification
Healthy Weight Range
—
based on BMI 18.5 to 24.9
Current Weight
—
converted to active unit view
Healthy Weight Range
—
This is the estimated weight range at your height corresponding to BMI 18.5 to 24.9.
Interpretation
—
Your interpretation summary will appear here.
BMI Category Band
Underweight
Normal
Overweight
Obesity
BMI Interpretation
Unit system—
Weight used—
Height used—
BMI score—
Category—
Healthy weight lower bound—
Healthy weight upper bound—
Difference to lower healthy bound—
Difference to upper healthy bound—
Summary band—
This calculator provides general estimates and is not medical advice. BMI is a screening tool, not a diagnosis. Individual health status varies. Consult a qualified professional for health-related decisions.
✦ Cal, AI Explanation
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Your BMI estimate is ready. Ask me what the category means, how the healthy range is calculated, or why BMI is only a general screening measure.

💡 BMI Notes

BMI is a general weight-to-height screening tool, not a full health assessment.
Muscle mass, frame size, age, and body composition can all affect interpretation.
The healthy weight range shown here is based on BMI 18.5 to 24.9.
BMI can be useful for quick screening, but it should not be treated as a diagnosis.
For a fuller picture, body fat, waist measures, and clinical context may also matter.

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Related Guides

What Is BMI→ Healthy Weight Range Explained→ BMI vs Body Fat→

How BMI is calculated

Body Mass Index, usually called BMI, is a simple ratio based on weight and height. It is used as a general screening tool to place a person into broad weight categories such as underweight, normal range, overweight, or obesity. Because it uses only two measurements, it is fast and widely used, but it is still a simplified estimate.

In metric units, BMI is calculated by dividing weight in kilograms by height in metres squared. In imperial units, a conversion factor is used to adjust pounds and inches into the same ratio. This calculator supports both systems and produces the same BMI result when the measurements are equivalent.

The formula

BMI = weight (kg) / [height (m)]²
or
BMI = 703 × weight (lb) / [height (in)]²
BMI is a general body-size screening estimate and should not be treated as a diagnosis.

What BMI categories mean

The standard adult BMI categories are usually interpreted as follows: below 18.5 is underweight, 18.5 to 24.9 is the general normal range, 25.0 to 29.9 is overweight, and 30.0 or above falls into obesity categories. These ranges help provide quick context, but they do not explain body composition, muscle mass, or distribution of weight.

That is why two people with the same BMI can still have different body compositions and different health contexts. BMI is useful for quick screening, but it works best alongside broader health information rather than on its own.

General adult BMI category guide

BMI Range Category General Meaning
Below 18.5UnderweightBelow the general healthy BMI range
18.5 to 24.9Normal RangeWithin the general healthy BMI range
25.0 to 29.9OverweightAbove the general healthy BMI range
30.0 and aboveObesityHigher BMI range requiring broader context

Why BMI has limits

BMI does not directly measure body fat. It does not distinguish between fat mass and muscle mass, and it does not account for where weight is carried on the body. For example, a muscular person may have a higher BMI without having excess body fat, while another person may fall inside the normal BMI range but still have a body composition that deserves a different interpretation.

That does not make BMI useless. It just means it should be used for what it is: a quick, general screening tool. If a more complete picture is needed, measurements such as waist size, body fat percentage, medical history, and professional assessment can matter as well.

Frequently Asked Questions

What is BMI?+
BMI stands for Body Mass Index. It is a ratio based on weight and height that is commonly used as a quick screening tool for broad weight categories.
What is a healthy BMI range?+
For adults, the commonly used healthy BMI range is 18.5 to 24.9. This calculator uses that range to estimate your healthy weight range for your height.
Does BMI measure body fat directly?+
No. BMI does not measure body fat directly. It uses only height and weight, so it cannot distinguish between muscle, fat, bone, or overall body composition.
Why can a muscular person have a high BMI?+
Because BMI does not separate muscle from fat, a person with high muscle mass can have a higher BMI even if their body fat level is not high. That is one reason BMI should be interpreted with context.
How is the healthy weight range calculated?+
The healthy weight range is calculated using the lower BMI boundary of 18.5 and the upper boundary of 24.9 for your height. This gives a general range of body weight that falls within the standard adult normal BMI band.