Waist-to-Height Ratio

Waist-to-height ratio (WHtR) calculator with Ashwell / NICE NG246 four-band classification. Imperial default; metric toggle; borderline annotation.

Waist

in cm

Waist circumference (in)

Measure midway between the lowest rib and the top of the hip bone — for most adults, just above the navel. Exhale normally, snug not tight.

How to measure your waist

Per NICE NG246 §1.2: measure midway between the lowest palpable rib and the top of the iliac crest (hip bone). Stand upright, breathe out normally, and hold the tape snug but not compressing the skin. Round to the nearest 0.25 in or 0.5 cm.

Height

ft + in cm

Height (ft)

Height (in)

Sex (optional)

Male Female

Optional — used only to label the tape landmark; thresholds are the same for adult men and women per Ashwell, NICE 2022.

Waist-to-Height Ratio

—

Enter waist and height.

Plain-language rule: Keep your waist less than half your height.
Target waist at your height: —

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How this is calculated

Formula: WHtR = waist circumference ÷ height (both in the same unit; result is dimensionless). A ratio of 0.5 means your waist is half your height, which is the primary Ashwell screening cut-point.

Bands (Ashwell 2016 / NICE NG246, sex-neutral, half-open on lower edge):

WHtR range	Category
< 0.4	Underweight
0.4 – < 0.5	Healthy
0.5 – < 0.6	Increased risk
≥ 0.6	Substantially increased risk

Worked example: waist 36 in (91.44 cm), height 5′10″ (177.8 cm) → WHtR = 91.44 ÷ 177.8 ≈ 0.514 → Increased risk. Target waist = 0.5 × 177.8 = 88.9 cm ≈ 35.0 in.

Borderline annotation: when the ratio falls within ±0.01 of a band edge (0.4, 0.5, or 0.6), a small note is shown beside the chip to soften the cliff-edge feel of a near-miss result.

Sources: Ashwell M, Gibson S. BMJ Open 2016;6:e010159 — bmjopen.bmj.com; NICE NG246 (Jan 2025) — nice.org.uk/guidance/ng246.

How we choose and check our formulas