What is a waist-to-height ratio?
The waist-to-height ratio (WHtR) is a simple measure of body shape that compares your waist circumference to your height. Because it focuses on how fat is distributed around the abdomen rather than overall body mass, many researchers consider it a better screening tool for central obesity and related health risks than body mass index alone.
WHtR is a single, unitless number. As long as you measure your waist and your height in the same unit, the units cancel out and the ratio is the same whether you work in centimetres, metres, inches, or feet.
How does the calculator work?
Enter your waist circumference and your height, choosing the unit for each from the dropdown. The calculator converts both measurements to a common unit, divides waist by height, and reports the ratio rounded to four decimal places. It then assigns a general health band based on the result.
For adults, the commonly used bands are:
- Below 0.40 — Underweight / take care: a very low ratio may indicate insufficient body mass.
- 0.40 to 0.49 — Healthy: the ratio associated with the lowest health risk.
- 0.50 to 0.59 — Overweight: raised central fat, with increasing risk.
- 0.60 and above — Obese: high central fat and the greatest associated risk.
A widely shared rule of thumb is “keep your waist circumference to less than half your height,” which corresponds to staying below a ratio of 0.50.
Formula
The waist-to-height ratio is the waist circumference divided by the height, both expressed in the same unit:
Worked examples
Example 1: A healthy ratio
A person with a waist circumference of 80 cm and a height of 170 cm has:
A ratio of about 0.4706 falls in the Healthy band (0.40 to 0.49).
Example 2: An overweight ratio
A person with a waist circumference of 100 cm and the same height of 170 cm has:
A ratio of about 0.5882 falls in the Overweight band (0.50 to 0.59).
Practical notes
- Measure your waist at the midpoint between the lowest rib and the top of the hip bone, breathing out normally and without pulling the tape tight.
- Use the same unit for both measurements, or let the calculator convert for you.
- WHtR is a screening indicator, not a diagnosis. The bands above are general guidance for adults and may not apply to children, athletes, or during pregnancy.
- For a complementary view of body composition, see the BMI calculator and the body fat calculator.