Jack Tools

BMI Calculator

Calculate BMI using metric, imperial, or mixed measurements and view the standard BMI category range.

Enter body measurements

cm
kg

BMI is a simple screening measure based on height and weight. It does not directly measure body fat, health, or fitness.

BMI result
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Category: —
BMI category
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Healthy weight range
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Height used
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Weight used
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BMI category guide

Underweight Below 18.5
Healthy weight 18.5 to 24.9
Overweight 25 to 29.9
Obesity 30 and above

How This BMI Calculator Works

This BMI calculator estimates body mass index using height and weight. BMI is a simple formula that compares weight with height to place the result into a standard category range.

You can use metric, imperial, or mixed measurements. In metric mode, enter height in centimetres and weight in kilograms. In imperial mode, enter height in feet and inches, and weight in stones and pounds.

The mixed mode is useful if you know your height in feet and inches but your weight in kilograms, or the other way around. The calculator converts the values for you before working out BMI.

It also estimates a standard healthy weight range for the height entered. BMI can be a useful screening tool, but it does not directly measure body fat, muscle mass, or overall health.

Measurement mode Choose metric, imperial, or mixed units depending on how you want to enter your height and weight.
BMI result The calculator estimates BMI from height and weight using the standard BMI formula.
BMI category The result is matched against the standard adult BMI category ranges.
Healthy weight range The calculator estimates the standard BMI healthy weight range for the height entered.
Back to calculator ↑

Example BMI Calculations

Metric example
Height175 cm
Weight70 kg
BMI22.9
Category = Healthy weight
Imperial example
Height5 ft 9 in
Weight11 st 0 lb
BMI22.7
Category = Healthy weight
Higher BMI example
Height168 cm
Weight82 kg
BMI29.1
Category = Overweight
Lower BMI example
Height180 cm
Weight57 kg
BMI17.6
Category = Underweight

BMI Calculator FAQs

BMI stands for body mass index. It is a simple calculation that uses height and weight to estimate a body size category.
In metric units, BMI is calculated by dividing weight in kilograms by height in metres squared.
No. BMI is a screening measure based on height and weight. It does not directly measure body fat, muscle mass, or overall health.
Yes. People with higher muscle mass can sometimes have a higher BMI without that reflecting body fat in the same way.
BMI is a general screening tool and may not reflect every individual equally. It is best interpreted with wider context rather than on its own.
The standard healthy BMI range for adults is 18.5 to 24.9, although interpretation can vary depending on age, ethnicity, and individual circumstances.

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