Waist to height ratio calculator
Your waist to height ratio (WHtR) is your waist circumference divided by your height. The calculator shows the value, rates it by the NICE guideline and gives the waist size that equals a ratio of 0.5.
Example: Unit: inches (in) · Waist circumference 33.5 in · Height 69 in → Waist to height ratio (WHtR): 0.49. Source: NICE NG246, NICE NG246 (2025): Overweight and obesity management – Rationale and impact (waist-to-height ratio: 0.5 to 0.59 increased risk, from 0.6 further increased risk). Updated: .
How it is calculated
How the waist to height ratio is calculated
WHtR = waist circumference ÷ height, both in the same unit. Example: a waist of 85 cm at a height of 175 cm gives 85 ÷ 175 = 0.49. Because top and bottom share a unit, the result is the same in centimetres and inches.
A simple rule of thumb: your waist should be smaller than half your height. At 175 cm (5 ft 9 in) that is 87.5 cm (34.4 in).
How to calculate your ratio
- Measure your waist: tape midway between the lowest rib and the top of the hip bone, relaxed after breathing out.
- Enter your height without shoes.
- Read the value, the rating and the waist at a ratio of 0.5.
Rating by NICE
| WHtR | Meaning |
|---|---|
| below 0.4 | unusually low, can point to being underweight |
| 0.4 to 0.49 | below the boundary of 0.5 |
| 0.5 to 0.59 | increased health risks |
| 0.6 and above | further increased risk |
The English NICE guideline on overweight and obesity (NG246, 2025) names a boundary around 0.5 for all ethnicities and both sexes; 0.5 to 0.59 corresponds to increased risks, and from 0.6 they rise further. The rating below 0.4 follows the Ashwell scale. Browning, Hsieh and Ashwell (2010) review the evidence for the 0.5 boundary.
Why not just BMI?
BMI says nothing about where fat sits. Two people with the same BMI can carry different amounts of belly fat. The waist to height ratio captures belly fat directly and, according to NICE, is also useful with high muscle mass. Using both values together makes sense.
Limits
- The calculator is meant for adults; children and teenagers have their own assessments.
- Pregnancy, fluid retention and operations distort the waist measurement.
- The value is an indicator, not a diagnosis.
Related: the BMI calculator rates weight against height, the body fat calculator estimates your fat share and the ideal weight calculator shows a weight range.
Frequently asked questions
What is a healthy waist to height ratio?
By the NICE guideline the boundary is 0.5: your waist should be smaller than half your height. From 0.5 to 0.59 health risks are increased, from 0.6 they rise further.
How do I measure my waist correctly?
By the WHO method: midway between the lowest rib and the top of the hip bone, at the end of a normal breath out, with the tape snug but not squeezing.
Is the ratio the same for women and men?
Yes. By NICE the boundary of 0.5 applies to both sexes and all ethnicities. That is an advantage over waist circumference alone.
How much waist do I need to lose to reach 0.5?
The calculator gives the waist at 0.5 (half your height) and the difference in centimetres or inches.
Is the waist to height ratio better than BMI?
It complements BMI, which says nothing about fat distribution. Some studies find the ratio more informative for cardiovascular risk, but neither replaces a medical examination.
Sources and legal basis
- NICE NG246: NICE NG246 (2025): Overweight and obesity management – Rationale and impact (waist-to-height ratio: 0.5 to 0.59 increased risk, from 0.6 further increased risk)
- Ashwell M, Gibson S (2016): Waist-to-height ratio as an indicator of ‘early health risk’: simpler and more predictive than using a ‘matrix’ based on BMI and waist circumference. BMJ Open 6:e010159
- Browning LM, Hsieh SD, Ashwell M (2010): A systematic review of waist-to-height ratio as a screening tool for the prediction of cardiovascular disease and diabetes: 0·5 could be a suitable global boundary value. Nutr Res Rev 23:247–269
- WHO 2008: WHO (2008): Waist circumference and waist-hip ratio – Report of a WHO Expert Consultation (measurement site of the waist)
As of: · Editorial policy
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