Waist to height ratio calculator
Two measurements, one division, and it tells you something BMI never can: where your weight actually sits.
Reading the bands
| Ratio | Reading |
|---|---|
| Under 0.4 | Low. Worth checking you are eating enough. |
| 0.4 to 0.5 | Healthy central adiposity. |
| 0.5 to 0.6 | Increased. The point at which NICE suggests acting. |
| 0.6 and over | High. |
Why the middle matters
Fat is not one substance in one place. Fat packed around the organs behaves differently from fat under the skin, and it tracks more closely with metabolic risk. Your waist is a crude but useful proxy for it, and dividing by height removes most of the unfairness of comparing a tall person's waist with a short person's.
The Body Roundness Index reads the same two measurements through a different equation, and thewaist to hip ratio compares your middle with your hips instead of your height.
Common questions
What is a healthy waist to height ratio?
Under 0.5. The guidance NICE published is memorable on purpose: keep your waist to less than half your height. Below 0.4 is treated as low, 0.5 to 0.6 as increased central adiposity and 0.6 or more as high.
Why is this better than BMI?
It is not better at everything, it is better at one thing: seeing where the weight is. Fat stored around the middle, near the organs, carries more metabolic risk than the same weight elsewhere, and BMI is blind to that. Someone can sit inside the healthy BMI band with a waist ratio above 0.5, and that combination is worth knowing about.
Does the same threshold apply to everyone?
The half your height rule is deliberately simple and is applied to adults generally, which is its strength and its weakness. It has not been validated equally across every population, and it is not intended for children under two or for pregnancy. Use it as a prompt to ask, not as a diagnosis.
Where exactly do I measure?
Halfway between the lowest rib you can feel and the top of your hip bone, standing, after breathing out, with the tape level and snug but not pulled tight. That is the World Health Organization's landmark, and it is the one the thresholds on this page were built on. Not where your trousers sit. Measuring in the same place each time matters more than the exact landmark.
Sources
Every figure above comes from one of these. Check them.
- NICE guideline NG246 (2025). Overweight and obesity management, including the waist to height ratio recommendation
- Ashwell M, Gunn P, Gibson S (2012). Waist-to-height ratio is a better screening tool than waist circumference and BMI for adult cardiometabolic risk factors: systematic review and meta-analysis. Obesity Reviews 13(3)
- Thomas DM et al. (2013). Relationships between body roundness with body fat and visceral adipose tissue emerging from a new geometrical model. Obesity 21(11)
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This is not medical advice. Body Numbers is a calculator. It does not diagnose, treat or monitor any condition, and no number it produces should replace a conversation with a doctor or a dietitian. If a result worries you, or if you are pregnant, unwell, or under eighteen, speak to a health professional.
