Waist-Based Metabolic Risk Calculator

How it is calculated

The tool gives two separate readings from the same two numbers, both in centimetres. First the waist-to-height ratio: WHtR = waist ÷ height, shown to two decimals. Below 0.40 is labelled the underweight range, 0.40 to under 0.50 healthy, 0.50 to under 0.60 increased risk, and 0.60 or more high risk. Second, the waist alone is compared with sex-specific limits: for men increased risk from 94 cm and high risk from 102 cm, for women 80 cm and 88 cm. Finally it prints a target, height × 0.5, as the waist to stay under. The two readings can disagree, and the ratio does not depend on sex. Height must be between 50 and 272 cm, the waist must be above 0 and smaller than the height; anything else shows no result. The limits are screening cut-offs and vary by population.

Common mistakes

• Entering waist in inches and height in centimetres, or the reverse: the ratio is only valid when both use the same unit, and the 94 and 102 cm limits only work for centimetres.
• Choosing the wrong sex and then comparing the waist status: the ratio is the same for both, but the waist status changes, as 90 cm is low risk for a man and high risk for a woman.
• Treating the two lines as one verdict: a man at 90 cm and 175 cm gets "Low risk" by waist and "Increased risk" by ratio, and both are worth reading.
• Measuring the waist over clothes or at the hip: the number you enter should be taken at the same level each time, otherwise the changes you see are measurement noise.
• Entering a waist that is equal to or larger than the height, for example by mixing units: this is not a possible body shape, so the tool shows no result.