Waist-to-Hip Ratio Calculator: Check Your Belly Fat Risk

How this calculator works

One division. That’s it.

Waist-to-hip ratio = waist circumference ÷ hip circumference

Both measurements go in the same unit (the form converts inches to centimetres for you), so the units cancel out. The result is rounded to two decimal places and compared with a cut-off that depends on your sex:

• Men: 0.90
• Women: 0.85

Below the cut-off, you see “Below the WHO risk threshold.” At or above it, the calculator flags the result as at or above the threshold for substantially increased metabolic risk. The calculator labels these as WHO thresholds; they are the figures widely quoted from the World Health Organization’s 2008 expert consultation on waist circumference and waist-hip ratio.

So a man with a 92 cm waist and 100 cm hips gets 0.92, which is over the line. A woman with a 78 cm waist and 98 cm hips gets 0.80, under hers.

Why the ratio matters

Two people can weigh the same and carry fat very differently. Fat packed around the middle tends to track with worse metabolic health than fat on the hips and thighs, and WHR is a cheap way to capture that.

The evidence is mostly observational, but it is large:

• In INTERHEART, a case-control study of 27,098 people across 52 countries, heart attack risk climbed with every quintile of waist-to-hip ratio. The top quintile had 2.52 times the odds of the bottom one after adjusting for age, sex, region and smoking. At any given BMI, bigger hips were linked to lower risk (Yusuf et al., 2005).
• A meta-regression of 15 prospective studies (258,114 people) found each 0.01 rise in WHR came with about a 5% higher risk of a cardiovascular event, in both men and women (de Koning et al., 2007).
• In the European EPIC cohort of 359,387 adults, WHR predicted risk of death even after accounting for BMI. BMI still mattered too (Pischon et al., 2008).

Associations, not proof that shrinking your ratio by itself fixes anything. But losing waist fat through training and a modest calorie deficit is rarely a bad bet.

Using your number

Measure on the same morning each fortnight, before breakfast, and log it. A single reading is noisy. A bloated evening waist can add a couple of centimetres easily.

If you’re over the line, the plan is boring and it works: a small deficit from the calorie calculator, lifting three or four days a week, and daily steps. Track your waist alongside photos and weekly scale averages, as laid out in our DIY physique tracking guide. Pair it with the waist-to-height ratio calculator for a second view that doesn’t depend on hip size.

Limitations and who it’s not for

• Tape technique. A centimetre either way on the waist moves the ratio by roughly 0.01. Measure the same spot every time.
• Big glutes, small waist. Lifters who build their hips can drop their WHR without any change in belly fat. And when hips shrink on a diet, the ratio can creep up.
• South Asians. The code uses one cut-off per sex for every ethnicity. In a hospital-based Bangalore study of 285 adults, waist circumference flagged abdominal obesity in more Asian Indians than WHR did, and none of the overweight men were flagged by WHR (Kurpad et al., 2003). A “pass” here is not an all-clear if your waist is large.
• Not for: pregnancy, under-18s, people with ascites or abdominal swelling, or anyone using it to self-diagnose. It is a screening number. Blood tests, blood pressure and a doctor’s assessment tell you about actual risk.

If you’re at or above the threshold, especially with diabetes or heart disease in the family, book a check-up and ask for fasting glucose, HbA1c and a lipid profile.