Waist-to-height ratio calculator

One measurement, one threshold, and a better read on your health than BMI gives: keep your waist under half your height.

Milo

Waist (cm)

Height (cm)

Your ratio will appear here.

How this is worked out

Divide your waist by your height. That’s it, and the target is 0.5.

ratio = waist ÷ height · healthy is 0.4 to 0.5

What makes it better than BMI is that it sees WHERE the weight is. Fat around the middle sits against your organs and is the kind that tracks with heart disease and type 2 diabetes. Fat on the hips and thighs behaves differently. BMI can’t tell the two apart because it only knows your total weight.

It also needs no separate charts. BMI thresholds shift by ethnicity and mislead at the extremes of height; the half-your-height rule holds up across populations, for men and women, and it’s memorable enough to actually use.

Measure at the navel, standing relaxed, breathing out normally. Same place, same way, every time.

The number is the easy part

Any calculator can hand you a figure. The hard bit is the next three months: eating roughly to it, noticing when it stops working, and changing it. Milo is a coach you text like a friend. You log what you ate in a sentence, and it learns your patterns, notices when your weight stalls, and adjusts the target from what you actually did rather than from a formula.

See how Milo works

Common questions

Is this really better than BMI?

For an individual, yes, and the research supports it: waist-to-height predicts cardiovascular and metabolic risk better than BMI in most large studies. BMI survives mainly because it’s cheap at population scale and needs no tape measure.

Where do I measure my waist?

At the navel, not at your natural narrowest point and not where your trousers sit. Stand up straight, arms down, breathe out normally. Don’t pull the tape tight enough to compress anything.

What if I'm very muscular?

Waist-to-height handles it far better than BMI does, because muscle mostly isn’t around your waist. A heavily built lifter who reads obese on BMI will usually sit comfortably healthy here.

My ratio is under 0.4. Is that a problem?

Possibly. Below 0.4 can mean underweight or very low body fat, which brings its own risks around hormones, bone density and immunity. If you’re there without trying, it’s worth a conversation with a doctor.

Other calculators

Body fat calculator — Your body fat percentage from a tape measure, no calipers needed.
Lean body mass calculator — How much of your weight isn't fat, and why it matters.
BMI calculator — Your BMI, plus an honest account of what it can't tell you.
TDEE calculator — How many calories you burn in a day, and what to eat for your goal.
Calorie deficit calculator — How long a given deficit takes to reach your goal weight.

These are estimates from population averages, not measurements of you. Individual metabolism varies by roughly ±10% around any formula. Nothing here is medical advice — if you have a health condition, are pregnant, or are under 18, talk to a healthcare professional before changing how you eat or train.