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Adult BMI calculator

Enter an adult height and weight for BMI. Choose the lower UK thresholds if they apply to your ethnic background, and read the number as one screening measure — not a verdict on your health.

Measurements
Which UK thresholds?
Your adult BMI27.7

Overweight range

BMI is one screening measure. It cannot distinguish muscle from fat and is not for everyone.

The useful bit

What the answer means

For most adults, the usual UK overweight threshold starts at 25 and the obesity threshold at 30. NICE uses lower thresholds of 23 and 27.5 for people from South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean backgrounds.

BMI cannot distinguish fat from muscle and needs care in several situations. The NHS adult calculator is not for under-18s, pregnancy, people with an eating disorder, or conditions that affect height; NICE also advises caution with high muscle mass and in adults aged 65 or over.

Transparent by design

How it works

  1. 1

    Use adult measurements

    Add height and weight in the units you know.

  2. 2

    Pick the relevant thresholds

    The calculator explains who NICE’s lower UK thresholds apply to.

  3. 3

    Keep the limits visible

    Use BMI as a screening measure alongside professional advice and other health information.

The mathsweight in kilograms ÷ height in metres squared

Plain answers

Questions people ask

How is BMI calculated?

Divide weight in kilograms by height in metres squared. Imperial measurements are converted before the same formula is used.

Who are the lower UK BMI thresholds for?

NICE recommends them for people from South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean backgrounds because cardiometabolic risk can occur at a lower BMI.

Can BMI tell muscle from fat?

No. The NHS and NICE both note that BMI can be less accurate for people with high muscle mass.

Who should not use this adult calculator?

The NHS says its adult calculator is not for under-18s, pregnancy, people diagnosed with or concerned about an eating disorder, or people with a condition that affects height.

Method and sources

Checked 19 October 2026. General information, not medical advice. Follow your prescriber and dispensing label.