A tool for your next question

Health calculators

Understand what each health calculator measures before using its result. These tools estimate quantities from your inputs; a number alone does not describe your health or provide a diagnosis.

10 selected toolsFind your calculator ↓

BMI is a screening measure

BMI is weight in kilograms divided by squared height in metres. It does not directly measure body fat or diagnose disease. The CDC’s adult calculator is for adults aged 20 and older; child and teen assessment requires age- and sex-specific interpretation.

Use the right tool for the person

A general adult formula may not suit a child, pregnancy, an athlete or a person with a medical condition. Read the limitations on the individual tool and discuss health concerns or major diet changes with an appropriately qualified clinician.

FAQ

Frequently asked questions

Does BMI directly measure body fat? ▾
No. BMI is a ratio of weight to squared height. It is a screening measure considered alongside other information, not a direct body-fat measurement or a diagnosis.
What is the difference between BMR and TDEE? ▾
BMR estimates energy used at rest under defined conditions. TDEE estimates total daily energy use including activity. The chosen equation and activity assumption affect the result.
Can I use adult BMI categories for a child? ▾
Do not interpret a child’s result using adult categories. Children and teens need age- and sex-specific assessment; use a suitable pediatric reference or speak with their healthcare professional.

Sources & Methodology

This topic page helps you choose a tool. Read the individual calculator’s assumptions, source dates and limitations before relying on its estimate.

Looking for something else? Search the full directory or choose your country.