A waist of 88 cm at a height of 170 cm gives a waist-to-height ratio of 0.52, which is in the increased health risk range. Keeping your waist under half your height, 85 cm here, keeps the ratio under 0.5.
What this calculates
Enter your height and waist, in centimetres or in feet and inches. This divides the waist by the height, places the ratio in the categories of the NICE guideline NG246, and shows the waist that is half your height and how far yours is above or below it. The units follow your country but can be switched.
The formula
Ratio
ratio = waist ÷ heightTarget
target waist = height ÷ 2Both must be in the same unit. Below 0.4 is "take care", 0.4 to 0.49 is healthy, 0.5 to 0.59 is increased risk and 0.6 and over is high risk.
Worked example
At the same height, 72 cm gives exactly 0.40 (healthy), 85 cm gives 0.50 (increased risk) and 102 cm gives 0.60 (high risk).
When to use it, and the mistakes to avoid
Use it as a quick check on your health risk, to set a waist-size goal, or to track change over time alongside your weight.
The mistakes that cost the most:
- Measuring in the wrong place. Use halfway between the ribs and hips, not at the belt.
- Mixing units. Waist and height must be in the same unit; the calculator handles it if you pick one system.
- Pulling the tape tight. It reads low and falsely reassures.
- Using it as a diagnosis. It is a screening measure only.
- Ignoring a result near the edge. 0.49 and 0.50 are close; the trend matters more.
FAQ
What is a healthy waist-to-height ratio?
Between 0.4 and 0.49. A ratio of 0.5 or more means more fat around the middle and a higher risk of type 2 diabetes and heart disease, and 0.6 or more is high risk. The simple rule is to keep your waist under half your height.
How do I measure my waist?
Stand up straight, find the point halfway between the bottom of your ribs and the top of your hips, wrap a tape measure around it, and read it after breathing out gently. Do not pull the tape tight or hold your breath in. Measure your height without shoes.
Why use this instead of BMI?
BMI ignores where fat is carried. Fat around the middle is linked to more health risk than fat on the hips or legs, and waist-to-height picks that up. It also needs no weight and works across heights and, for adults, across age and sex. The two measure different things, so use both.
Does it apply to everyone?
The same cut-offs are used for men and women and for adults and children over 5. It is a screening measure, not a diagnosis, and it is less reliable if you are very muscular, pregnant, or under 5. If you are worried about your result, speak to a doctor or practice nurse.
Where do the categories come from?
They follow the UK National Institute for Health and Care Excellence guideline on overweight and obesity management (NG246): below 0.4 take care, 0.4 to 0.49 healthy, 0.5 to 0.59 increased risk, and 0.6 and over high risk. Guidelines can change, so check NICE for the latest.