Conicity Index Calculator
Calculate the conicity index (C index) from waist, weight and height to assess abdominal fat distribution, with sex-specific cut-offs for cardiovascular risk.
How it works
C index = waist (m) ÷ [0.109 × √(weight (kg) ÷ height (m))] · cut-offs for high coronary risk: men ≥ 1.25, women ≥ 1.18
Valdez (1991) proposed the conicity index to compare a person’s waist with the circumference of a cylinder of the same weight and height: the constant 0.109 comes from an average body density of 1,050 kg/m³. A value of 1.00 means a perfectly cylindrical trunk; the more fat sits around the abdomen, the more the body looks like a double cone and the higher the index — the theoretical maximum is about 1.73. Pitanga and Lessa derived cut-offs of 1.25 for men and 1.18 for women for high coronary risk in Brazilian adults.
Worked example
A man with a 90 cm waist, 80 kg and 175 cm: √(80 ÷ 1.75) = 6.76; 0.109 × 6.76 = 0.737; C index = 0.90 ÷ 0.737 = 1.22, just below the 1.25 cut-off for men. His waist-to-height ratio is 0.51.
Sources: Valdez R (1991) A simple model-based index of abdominal adiposity. J Clin Epidemiol 44:955–956 · Pitanga FJG, Lessa I (2005) Anthropometric indexes of obesity as an instrument of screening for high coronary risk in adults. Arq Bras Cardiol 85:26–31
Frequently asked questions
What is a normal conicity index?
There is no universal normal range, but values below about 1.25 in men and 1.18 in women were associated with lower coronary risk in the study most often cited. The index ranges from 1.00 (cylinder) to about 1.73 (double cone).
How is it different from BMI?
BMI uses only weight and height, so it cannot tell where fat is stored. The conicity index adds the waist and adjusts it for body size, so it reflects abdominal (visceral) fat, which is more closely linked to heart disease and diabetes.
Where should I measure the waist?
Most studies of the conicity index measured midway between the lowest rib and the top of the hip bone, at the end of a normal breath out, with the tape horizontal and snug but not compressing the skin.
Are the cut-offs valid for everyone?
They came from adults in Salvador, Brazil, and other studies have proposed slightly different values for other populations, older adults and adolescents. Use the result alongside waist-to-height ratio and clinical risk factors.
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This calculator is an educational aid for nutrition and health professionals. It does not replace a clinical assessment — measurement technique strongly affects the result, so interpret it with a qualified professional.