Waist-to-Height Ratio Calculator
Divide your waist by your height to get the waist-to-height ratio, a simple screen for central fat that many studies find more useful than BMI.
Keep your waist under half your height — this checks whether you do.
How the waist-to-height ratio calculator works
The waist-to-height ratio is waist circumference divided by height, in the same units. The widely used rule is "keep your waist to less than half your height": a ratio under 0.5 is associated with lower cardiometabolic risk, 0.5–0.59 with increased risk, and 0.6 and above with high risk. Because it measures where fat sits rather than total weight, it flags central fat that BMI can miss and it needs no age or sex adjustment in adults.
Measure the waist at the midpoint between the bottom rib and the top of the hip bone, at the end of a normal breath out, with the tape snug but not compressing the skin.
Formula: WHtR = waist ÷ height
Worked examples
| Inputs | Waist-to-height ratio | Note |
|---|---|---|
| 85 cm waist, 175 cm tall | 0.49 | under the 0.5 line |
| 96 cm waist, 175 cm tall | 0.55 | over 0.5 — increased risk band |
| 34 in waist, 5 ft 9 in tall | 0.49 | the ratio is the same in any unit |
| 108 cm waist, 170 cm tall | 0.64 | the 0.6 band |
FAQFrequently asked questions
Why waist-to-height rather than BMI?
BMI cannot tell fat from muscle or say where fat sits. Fat around the abdomen is the kind linked to heart disease and diabetes, and the waist-to-height ratio captures it with one tape measurement.
What is a healthy waist-to-height ratio?
Under 0.5 for adults — "keep your waist to less than half your height". Several national guidelines have adopted this message; 0.6 and above is treated as high risk.
How do I measure my waist properly?
Midway between the bottom of your ribs and the top of your hip bones, roughly level with the navel, at the end of a normal exhale, tape snug but not tight, directly on the skin.
Does it work for children or very tall people?
The 0.5 boundary was derived for adults. For children the ratio is used with age-specific reference charts; ask a doctor rather than applying the adult rule.
Where these figures come from
- Mifflin MD et al., "A new predictive equation for resting energy expenditure in healthy individuals", Am J Clin Nutr 1990 — the BMR equation used here
- World Health Organization — Waist circumference and waist–hip ratio (2008 expert consultation) — waist-to-hip cut-offs
- Tanaka H, Monahan KD, Seals DR, "Age-predicted maximal heart rate revisited", J Am Coll Cardiol 2001 — 208 − 0.7 × age
- Nathan DM et al., "Translating the A1C assay into estimated average glucose values" (ADAG), Diabetes Care 2008 — eAG = 28.7 × A1c − 46.7
- Mosteller RD, "Simplified calculation of body-surface area", N Engl J Med 1987 — BSA = √(height × weight / 3600)
- NHS — national health guidance
Last checked: September 2026. The equations are fixed by their published papers and do not change with tax years or regulations; the thresholds quoted in verdicts name the body that set them.