Check your waist-to-height ratio, a simple measure of central fat. The rule of thumb is to keep your waist below half your height. Free, private, and runs entirely in your browser.
Divide your waist circumference by your height in the same unit. A ratio under 0.5 means your waist is less than half your height, which is the usual target. Higher ratios point to more fat around the middle.
What is a good waist-to-height ratio? Between 0.4 and 0.49 is generally seen as healthy. From 0.5 the risk of heart and metabolic problems rises, and 0.6 or more is high.
Does it work for all heights? It is designed to work across heights because it scales waist size to body size, which is one of its advantages over a single waist limit.
A person who is 175 cm tall has a waist of 85 cm. The ratio is 85 ÷ 175 = 0.486, in the healthy range. Half of 175 cm is 87.5 cm, so the waist should stay below that.
Is it better than BMI? It looks at fat around the abdomen, so it can flag risk in people whose BMI is normal. It does not replace a clinical assessment.
Why under 0.5? Large studies found that risk factors start to rise once the waist exceeds about half the height, so 0.5 became the simple rule.
The idea that waist should be less than half of height was proposed in the 1990s, and later studies suggested that the ratio predicts cardiovascular and metabolic risk at least as well as BMI. It has since been adopted in guidance from bodies such as the UK National Institute for Health and Care Excellence.
Use this calculator for a quick check of central body fat, or to set a waist target as part of a health plan. This is general information, not medical advice. Talk to a doctor or other qualified professional about your own results.
What waist size should I aim for? Under half of your height. The calculator shows the exact number for your height.
Does muscle affect the ratio? Muscle affects weight and BMI but not waist circumference as much, which is why the ratio can be more informative for athletic people.