Waist-to-height ratio calculator
Divide your waist by your height to get your waist-to-height ratio. The simple guideline is to keep your waist below half your height, a ratio under 0.5. The calculator shows the ratio, its category and the waist size that would give 0.5.
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How to use it
- Choose centimeters or inches.
- Measure your waist and height and enter them.
- Read the ratio, its category and the waist size that equals half your height.
How it works
WHtR = waist circumference ÷ height, both in the same unit, so the answer is the same in centimeters and inches. The categories follow the bands used in NICE guidance on overweight and obesity:
| Ratio |
Meaning |
| below 0.4 |
take care – may be underweight |
| 0.4 to 0.49 |
no increased risk |
| 0.5 to 0.59 |
increased risk |
| 0.6 or more |
further increased risk |
“Keep your waist to less than half your height” is the rule of thumb promoted by Margaret Ashwell and colleagues.
Worked example
A person who is 175 cm tall with an 80 cm waist:
- 80 ÷ 175 = 0.46, in the 0.4–0.49 band
- half of the height is 87.5 cm, so a waist up to that size keeps the ratio below 0.5
With a 90 cm waist at 170 cm tall the ratio is 90 ÷ 170 = 0.53, in the increased-risk band.
Limits and tips
- The ratio is a screening measure, not a diagnosis. It does not replace a medical check-up.
- Measure at the same time of day and in the same way. A 1 cm difference in the tape position moves the ratio by about 0.006 for an adult of average height.
- It is not designed for pregnancy, and children need age-specific charts. For medical questions, ask your doctor.
Frequently asked questions
What is a healthy waist-to-height ratio?
The popular guideline is to keep your waist circumference under half your height, a ratio below 0.5. NICE in the UK describes 0.4 to 0.49 as no increased risk, 0.5 to 0.59 as increased risk and 0.6 or above as further increased risk.
How do I measure my waist?
Stand relaxed and measure around the middle of your torso, halfway between the lowest rib and the top of the hip bone, after breathing out normally. Keep the tape level and snug but not squeezing the skin.
Is WHtR better than BMI?
It answers a different question. BMI uses weight and ignores where fat sits, while WHtR tracks belly fat, which is linked to heart and metabolic risk. Reviews such as Ashwell, Gunn and Gibson (Obesity Reviews, 2012) found it at least as good as BMI at flagging risk. Doctors often use both.
Does the ratio depend on age or sex?
The 0.5 boundary was proposed as a single value for men and women and for different heights. Children and older people can be assessed differently, so ask a doctor for individual advice.