BMI + waist-to-height ratio

Two simple screening measures instead of BMI alone. The calculator shows BMI, waist-to-height ratio (WHtR), a BriefRooms comment and general guidance. For adults.

Enter three values

No sex field is needed — the WHtR thresholds used here are the same for women and men.

kilograms
centimetres
centimetres; do not pull the abdomen in

How to measure your waist: find the bottom of the ribs and the top of the hips, then measure midway between these points after a relaxed breath out. This follows the NICE method.

Calculations run only in your browser. The values you enter are not sent to the server.

How is BMI interpreted?

For most adults, WHO defines overweight from BMI 25 kg/m² and obesity from 30 kg/m². BMI is a screening measure, not a direct measurement of body fat.

  • <18.5 — underweight
  • 18.5–24.9 — healthy range
  • 25.0–29.9 — overweight
  • 30.0–34.9 — obesity class I
  • 35.0–39.9 — obesity class II
  • ≥40 — obesity class III

Why waist-to-height ratio?

NICE recommends using WHtR alongside BMI in adults with BMI below 35 kg/m² as a practical estimate of central adiposity.

  • 0.40–0.49 — healthy central adiposity
  • 0.50–0.59 — increased central adiposity
  • ≥0.60 — high central adiposity

The simplest message is: keep your waist below half your height.

Important limitations

WHtR adds less information when BMI is ≥35 kg/m². BMI should be interpreted cautiously in people with high muscle mass, in older adults and in some ethnic groups where cardiometabolic risk can occur at lower BMI levels.

This tool is not intended for pregnancy, children or adolescents.

Method sources

The WHtR thresholds and the “waist below half your height” message follow NICE NG246.

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