The waist-to-height ratio (WHtR) is one of the simplest and most reliable body-fat screens: WHtR = waist ÷ height, measured in the same unit. The famous rule of thumb is keep your waist to less than half your height — a WHtR below 0.5. Because it scales waist to your own height, a single boundary works for nearly all adults of both sexes, and research finds it tracks heart-and-metabolic risk at least as well as BMI. It targets abdominal fat specifically, which matters more for health than overall weight.
Reviewed: June 20, 2026 · Author: Naveen P N, Founder — AI Calculator · Verified against: the standard WHtR definition and 0.5 boundary. Not medical advice.
The waist-to-height equation
Dividing waist by height gives a unitless number, so it doesn't matter whether you measure in centimetres or inches as long as both use the same unit. The standard bands are: under 0.5 healthy, 0.5 to 0.6 increased risk, and 0.6 or above high risk. Rearranging the boundary gives a concrete waist target — at any height, aim to keep your waist under half of it.
Worked example — 80 cm waist, 175 cm tall
Scenario: waist 80 cm, height 175 cm.
A ratio of 0.457 sits comfortably in the healthy band — the waist is about 46% of height, under the half-height limit of 87.5 cm. Watch how it moves with the waist at this height: 90 cm gives 0.514 (increased risk) and 105 cm gives 0.600 (high risk). That's the value of WHtR — a few centimetres of waist shift the band in a way the bathroom scale never shows, because it's the abdominal fat, not total weight, that's being flagged.
Frequently Asked Questions
Waist ÷ height in the same unit. 80 cm / 175 cm = 0.457. Scales waist to your size.
Under 0.5 — waist below half your height. 0.5–0.6 increased, ≥ 0.6 high risk.
Midway between lowest rib and hip bone, breathe out, tape snug. Same unit as height.
It targets abdominal fat and predicts risk at least as well; many use both together.
A screen, not a diagnosis — no muscle/fat split, not for pregnancy. See a professional.