Waist Ratio Calculator
Measure waist (and hip for WHR) to screen central adiposity — waist-to-height ratio or waist-to-hip ratio with established risk bands.
Calculate
Calculate
Measurements convert when you switch units
Result
The formula
Waist-to-height ratio (WHtR) = waist ÷ height. NICE and multiple health bodies use ~0.5 as an action threshold for increased cardiometabolic risk. Waist-to-hip ratio (WHR) = waist ÷ hip; WHO cutoffs: men ≥0.90 and women ≥0.85 indicate substantially increased risk.
Worked example
- Waist 85 cm, height 175 cm
- WHtR = 85 ÷ 175 = 0.49
- Category: healthy (below 0.5 action level)
Result: 0.49 — Healthy WHtR
Interpreting waist ratios
Central fat carries different metabolic risk than fat stored elsewhere — waist measures capture that better than weight alone.
Waist-to-height (WHtR)
A simple rule: keep waist below half your height (WHtR < 0.5). Values 0.5–0.6 suggest increased risk; above 0.6, higher obesity-related risk in screening tools.
Waist-to-hip (WHR)
WHR compares abdominal fat to hip fat. WHO classifies men with WHR ≥0.90 and women ≥0.85 as having substantially increased cardiometabolic risk.
How to measure
Stand relaxed, measure waist at midpoint between lowest rib and iliac crest (or navel level consistently). Hips at widest gluteal circumference. Tape horizontal, snug not tight.
Interesting facts
“Keep waist to half height”
Public health campaigns (e.g. UK NICE guidance context) popularized WHtR < 0.5 as an easy screening message.
Better than BMI alone?
Waist measures add information about fat distribution — especially when BMI is normal but central fat is high (“normal-weight obesity”).
Sex differences in WHR
Women naturally store more hip/thigh fat; WHR cutoffs differ by sex in WHO guidance.
Complements body fat
Circumference ratios do not replace DEXA or Navy body fat estimates — they are quick field screens.
One measurement, two ratios
This tool supports WHtR (needs waist + height) and WHR (needs waist + hip) — pick the mode that matches your measurements.
Frequently asked questions
Many guidelines suggest WHtR below 0.5. Between 0.5 and 0.6 is often flagged as increased risk; above 0.6, higher risk.
WHO: men ≥0.90 and women ≥0.85 indicate substantially increased risk. Below those is generally lower risk in screening.
Midpoint between bottom rib and hip bone, or consistently at navel level — same spot each time matters more than which textbook point you pick.
WHtR needs only waist and height — easy to remember. WHR adds hip and sex-specific cutoffs — both screen central adiposity.
Yes — this is sometimes called “normal-weight obesity.” Waist-based ratios can flag central fat risk even when BMI looks healthy, which is why they are used alongside BMI, not instead of it.
Central fat tends to increase with age even without major weight gain, so waist ratios can rise over time. Most published risk thresholds are for adults and are not validated for children.
Monthly or quarterly is plenty for tracking trends. Measure at the same time of day, ideally before eating, and use the same landmark each time for consistent results.
References
- Waist circumference and waist-hip ratio report WHR cutoffs and measurement protocol.
- Obesity: identification and classification WHtR context in UK clinical guidance.