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BMI and context

Compute BMI in metric or imperial units, see the WHO category, and see which weights at your height correspond to BMI 18.5, 25, 27, 30, 35 and 40. Label thresholds are shown as label wording, not as an eligibility decision.

By FormBlends editorial teamAssumptions checked September 4, 2026Runs in your browser; nothing is sent to a server

Inputs

lb
ft
in

Context

Enter weight and height. You get the BMI, the WHO category, and the weight ranges at your height that correspond to each cut point.

Formulashown in full, nothing hidden
BMI (kg/m²)            = weight (kg) / height (m)²
weight for a given BMI = BMI x height (m)²
1 lb = 0.45359237 kg;  1 in = 2.54 cm

BMI is a ratio of weight to height squared. It says nothing about body composition, fat distribution, or health on its own; it is used in labels and trials because it is cheap and reproducible.

Assumptions, checked September 4, 2026

  • Categories are the WHO adult classification: under 18.5 underweight, 18.5 to under 25 normal range, 25 to under 30 overweight, 30 and above obesity (classes I, II and III at 30, 35 and 40).
  • The Wegovy and Zepbound labels describe use in adults with BMI 30 or more, or 27 or more with at least one weight-related condition, alongside a reduced-calorie diet and increased activity. That is label wording, not an eligibility decision; a prescriber makes that decision.
  • BMI is not adjusted for age, sex, ethnicity, muscle mass or pregnancy. Some clinical bodies use different cut points for some populations.

This calculator is an arithmetic aid for medication a licensed prescriber has already prescribed. It does not recommend a dose. Confirm any result with your prescriber or pharmacist before use.

Sources

  1. World Health Organization: A healthy lifestyle, WHO recommendations (BMI classification)
  2. CDC: Adult BMI categories
  3. Wegovy (semaglutide) prescribing information, NDA 215256, Drugs@FDA
  4. Zepbound (tirzepatide) prescribing information, NDA 217806, Drugs@FDA

Read before you use it

Guides for this calculator

BMI: what it measures, and where the label thresholds come from

The formula, the WHO categories, why the Wegovy and Zepbound labels mention 27 and 30, and what BMI cannot tell you about your body.

Updated September 4, 2026

Educational, not medical advice. Read the medical disclaimer.