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Waist-to-Height Ratio Calculator

Calculate waist-to-height ratio and understand the simple “keep your waist below half your height” screening message.

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How this calculator works

Waist-to-height ratio adds information BMI misses: where some body mass is carried. Central fat is more closely linked with metabolic risk than weight alone.

The ratio is still a screening measure. It cannot diagnose diabetes, cardiovascular disease or any other condition, and measurement technique can shift the number.

Formula

Waist-to-height ratio = waist circumference ÷ height, using the same unit for both. A result below 0.5 is a widely used simple screening threshold.

How to use the result

A result at or above 0.5 is a prompt to look at the wider picture—blood pressure, lipids, glucose, activity and medical history—not a reason to panic.

Measure consistently at the midpoint between the lowest rib and top of the hip bone after a normal exhale. Do not pull the tape into the skin.

Get a more reliable result

Measure height without shoes. For waist, use a non-stretch tape at the midpoint between the lowest rib and top of the hip bone, after a normal exhale. Keep the tape level and avoid pulling it into the skin. Repeat twice and use the average if the readings are close.

Worked example: an 82 cm waist divided by 170 cm height gives 0.48. A common public-health message is to keep waist below half of height, but the ratio is a screening aid—not a diagnosis or a substitute for blood pressure, lipids and glucose.

Common errors that change the answer

  • Using trouser size, which is a garment label rather than an anatomical measurement.
  • Measuring at the narrowest point one month and at the navel the next.
  • Interpreting a small change as real when tape tension and breathing were not standardized.

What to do next

  • Use a non-stretch tape and stand relaxed.
  • Repeat twice and use the average when measurements differ.
  • Track every four weeks; daily waist measurement adds noise.

Guides that support this calculator

Body recomposition guide→How to interpret FFMI→Measure waist correctly→

Frequently asked questions

Is this better than BMI?

It answers a different question and can complement BMI by reflecting central size. Neither is a complete health assessment.

Where exactly should I measure?

Guidelines commonly use the midpoint between the lowest rib and iliac crest. Consistency matters more than chasing a millimetre.

Does 0.5 diagnose obesity?

No. It is a public-health screening threshold that can indicate value in further assessment.

Sources and methodology

Reviewed September 2026

NICE — Waist-to-height ratio guidance ↗
Health note: This calculator provides a general educational estimate for adults. It does not diagnose a condition or replace advice from a doctor or registered dietitian. Seek professional guidance for pregnancy, an eating disorder, a medical condition, medication-related needs, or concerning symptoms.