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NICE band {{ resultsReady ? bandLabel : '—' }} Half-height line {{ resultsReady ? formatWaist(computation.values.half_height_waist_cm) : '—' }}
Changing the unit converts the value without changing the measurement.
Waist and height may use different source units; both are normalized before division.
Three decimals is the default; full precision remains canonical for bands and exports.
Ratio breakdown
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Calculation method:
Both measurements are converted to centimetres before division, so mixed input units are safe.
waist-to-height ratio = waist ÷ height

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Interpretation
Current screening band

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Who the bands cover

NICE uses these bands for adults with BMI below 35 kg/m² and for children and young people aged 5 or over. For anyone aged 5–17, use the result with a parent or carer and alongside child BMI guidance.

When not to rely on this result

Do not use it as a diagnosis or as a stand-alone screen during pregnancy, under age 5, with an eating disorder, a growth or height-affecting condition, or for an adult BMI of 35 kg/m² or more. Seek professional advice if the result or measurement concerns you.

The chart renderer is unavailable. The ratio and threshold guide remain available.

ReferenceRatioWaist at this heightMeaningCopy
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Where body fat is carried can matter as well as total body size. Waist-to-height ratio compares waist circumference with standing height as a practical estimate of central adiposity, the concentration of fat around the abdomen. It is used alongside body mass index and other health information rather than as a diagnosis by itself.

The ratio has no unit because waist and height are expressed in the same unit before division. A waist of 90 cm and height of 180 cm gives 0.50; the same measurements in inches give the same result. The familiar “keep your waist below half your height” message is the boundary between NICE's healthy and increased central-adiposity bands.

Measurement technique can change the result enough to cross a boundary. For a repeatable waist measurement:

  • find the midpoint between the bottom of the ribs and the top of the hips;
  • keep the tape level and snug without compressing the skin;
  • measure after breathing out naturally rather than pulling the abdomen in.

Height should be current and measured without shoes. Repeating both measurements under similar conditions is more informative than comparing a careful measurement with an old estimate from clothing size or memory.

NICE applies these bands to adults with BMI below 35 kg/m² and to children and young people aged 5 or over. Children need age-appropriate BMI guidance and support from a parent or carer. Pregnancy, eating disorders, growth or height-affecting conditions, and adult BMI of 35 kg/m² or more need different clinical context.

How to Use This Tool:

Use a current waist measurement and standing height; the two fields may use different units.

  1. Enter Waist circumference and choose cm, m, in, or ft. Changing the unit converts the measurement rather than reinterpreting the same digits.
  2. Enter Standing height and its unit. Both measurements are converted to centimetres before division.
  3. Read Ratio breakdown and Interpretation, then compare the current waist with the half-height and high-threshold waist values. Ratio precision changes display only.

Interpreting Results:

Band assignment uses the unrounded ratio. A displayed value near 0.40, 0.50, or 0.60 can therefore appear equal to a boundary while its full-precision value remains just below or above it.

  • Below 0.40 is reported as Below reference range. Lower is not automatically better; first check measurement quality and wider health context.
  • From 0.40 to below 0.50 is Healthy central adiposity.
  • From 0.50 to below 0.60 is Increased central adiposity.
  • At or above 0.60 is High central adiposity.

Technical Details:

Waist and height are normalized to centimetres before the ratio is calculated. Because both quantities have the same dimension, centimetres cancel and the result is unitless. Mixed input units are therefore safe when each unit is selected correctly.

Formula Core:

The ratio and height-specific waist thresholds use full-precision centimetre values.

R=WcmHcm Whealthy floor=0.40×Hcm Whalf height=0.50×Hcm Whigh threshold=0.60×Hcm
Input unitCentimetres per unit
cm1
m100
in2.54
ft30.48

Rule Core:

BandExact ruleNICE interpretation
Below reference rangeR < 0.40Below the named healthy central-adiposity range
Healthy central adiposity0.40 ≤ R < 0.50No increased health risk from this measure
Increased central adiposity0.50 ≤ R < 0.60Increased health risk
High central adiposityR ≥ 0.60Further increased health risk

A result is accepted only when waist resolves to 30–250 cm, height to 50–275 cm, and the ratio to 0.10–2.00. These are calculator validation limits, not additional NICE risk bands.

For an 84 cm waist and 172 cm height, the unrounded ratio is 0.488372…. The result is healthy, half-height is 86 cm, and the current waist is 2 cm below that boundary. Choosing two, three, or four decimal places changes only how those values are shown.

Limitations and Health Cautions:

Waist-to-height ratio is a screening measure, not a diagnosis. It does not capture blood pressure, blood glucose, lipids, fitness, family history, body composition, or the reasons a waist measurement may be unusual.

Discuss an increased or high result with a healthcare professional when it causes concern or accompanies other risk factors. Do not rely on these bands as a stand-alone assessment during pregnancy, under age 5, with an eating disorder or height-affecting condition, or when adult BMI is 35 kg/m² or more.

References: