The formula
How to calculate waist to hip ratio
Waist to hip ratio describes where the body stores fat. Abdominal fat carries more metabolic risk than fat on the hips and thighs, which is why the ratio predicts cardiovascular outcomes better than BMI does.
Measure the waist midway between the lowest rib and the iliac crest, and the hips at their widest, standing relaxed with the tape horizontal. Measure after breathing out normally, not while holding your stomach in.
What to enter:
- Waist circumference (cm) — midway between the lowest rib and the top of the hip bone
- Hip circumference (cm) — at the widest point of the buttocks
No submit button: type and the answer moves. Your inputs end up in the link, so the page can be shared already filled in.
Consistency in how the underlying measurements are taken matters more than precision to the last decimal — measuring at the same time of day, in the same state of rest or hydration, makes readings taken weeks apart genuinely comparable in a way that a single very precise reading on its own is not.
Why waist to hip ratio matters
The formula behind waist to hip ratio comes from published research rather than being invented for this page, and it is presented here exactly as it appears in the literature it is drawn from — the value of a calculator is applying it correctly and instantly, not reinventing it.
It is most useful tracked over time rather than read once — a single reading tells you where you are today, while the same calculation repeated weeks or months apart, using the same method each time, shows the direction things are actually moving in.
None of the figures produced on this page are intended to replace a proper assessment, and nothing here should be read as a diagnosis or a treatment recommendation. What a calculator like this is good for is preparation — arriving at an appointment with an actual number already in hand, rather than a vague sense of a change, tends to make that conversation more useful for everyone involved.
In practice, this kind of figure is often calculated more than once with slightly different inputs to see how sensitive it is — trying a measurement taken this morning against one taken yesterday evening, for instance, to see how much normal daily variation actually moves the result. That habit is a good one: it builds a feel for how much a single reading can be trusted on its own before drawing any conclusion from it.
Worked example
A concrete run-through, using the values already in the fields:
- Waist circumference: 88 cm
- Hip circumference: 100 cm
That gives:
- Waist to hip ratio: 0.88
- Waist for a 0.90 ratio: 90 cm
- Waist for a 0.85 ratio: 85 cm
Those starting figures exist only to show the calculation working, not as a target or a reference value to compare yourself against — replace them with your own measurements in the calculator above and the same formula applies exactly as shown.
Reading the result
The World Health Organization treats above 0.90 in men and above 0.85 in women as substantially raised risk. The thresholds shown above are the waist measurements those ratios correspond to at your hip size.
Where this goes wrong. The ratio can stay flat while both measurements grow, hiding real weight gain. Track waist circumference alongside it, and treat this as general information rather than a clinical risk assessment.
As with any general-purpose formula, the result here is an estimate derived from population averages, not a measurement specific to you — a reasonable starting point for a conversation with a qualified professional, not a replacement for one. Nothing on this page is medical advice.
For cardiovascular and metabolic risk, generally yes, because it captures fat distribution rather than just weight. BMI remains useful at population level and is easier to measure consistently.
Below 0.90 for men and below 0.85 for women, using WHO thresholds. Lower is broadly better, though the relationship flattens out at the low end.
The headline figure is waist to hip ratio. With 88 cm waist circumference and 100 cm hip circumference, that comes to 0.88. Change any field and the figure moves with it.
It uses a published formula applied exactly as defined, so the arithmetic itself is precise — but the formula is a population-level estimate, and individual results can vary from it for reasons the formula has no way to account for. Treat the output as a reasonable estimate rather than a measured or diagnostic value.
For most people, yes — a single reading is a snapshot, while the same measurement repeated consistently over weeks or months shows a trend, which is generally more informative than any one figure taken in isolation.
Small differences between calculators usually come down to which published formula or reference dataset each one uses — several equations in this area exist in more than one accepted version. This page states the specific formula used in the section above, so it is possible to check directly whether another source is using the same one.