Conicity Index
Conicity Index estimates central (truncal) adiposity from waist circumference, weight, and height using the Valdez 1991 formula, which compares the waist to a cylinder of the same weight and height. It runs from about 1.1 (lean, cylindrical) upward; higher values mean more central fat. These percentiles are derived from NHANES 2015-2023 (US adults 20+, n=18,889), a population with a measured adult obesity rate of 42.4% by BMI (Hales et al. 2020). See the methodology page for the pooled-cycle derivation and population context.
Data source: NHANES (CDC), derived Conicity Index percentiles About this study
Reference population: US adults aged 20 and over from three pooled NHANES cycles (2015-2016, 2017-March 2020, 2021-2023), nationally representative
Conicity Index Norms Chart by Age and Sex (index)
| Age | Sex | Percentile | ||||
|---|---|---|---|---|---|---|
| 5th | 25th | 50th | 75th | 95th | ||
| 20-24 | Male | 1.108 | 1.170 | 1.227 | 1.296 | 1.384 |
| Female | 1.100 | 1.169 | 1.223 | 1.290 | 1.404 | |
| 25-29 | Male | 1.124 | 1.190 | 1.250 | 1.310 | 1.402 |
| Female | 1.123 | 1.190 | 1.246 | 1.319 | 1.421 | |
| 30-34 | Male | 1.150 | 1.226 | 1.277 | 1.339 | 1.424 |
| Female | 1.139 | 1.206 | 1.272 | 1.342 | 1.438 | |
| 35-39 | Male | 1.174 | 1.247 | 1.300 | 1.348 | 1.434 |
| Female | 1.149 | 1.223 | 1.277 | 1.348 | 1.449 | |
| 40-44 | Male | 1.189 | 1.264 | 1.306 | 1.351 | 1.434 |
| Female | 1.165 | 1.233 | 1.290 | 1.348 | 1.438 | |
| 45-49 | Male | 1.193 | 1.272 | 1.312 | 1.362 | 1.457 |
| Female | 1.172 | 1.228 | 1.286 | 1.358 | 1.445 | |
| 50-54 | Male | 1.206 | 1.286 | 1.330 | 1.375 | 1.462 |
| Female | 1.176 | 1.258 | 1.322 | 1.373 | 1.458 | |
| 55-59 | Male | 1.224 | 1.297 | 1.344 | 1.390 | 1.467 |
| Female | 1.177 | 1.270 | 1.326 | 1.384 | 1.468 | |
| 60-64 | Male | 1.244 | 1.304 | 1.357 | 1.412 | 1.488 |
| Female | 1.190 | 1.280 | 1.336 | 1.389 | 1.458 | |
| 65-69 | Male | 1.248 | 1.315 | 1.365 | 1.412 | 1.483 |
| Female | 1.212 | 1.288 | 1.348 | 1.411 | 1.486 | |
| 70-74 | Male | 1.262 | 1.339 | 1.381 | 1.429 | 1.493 |
| Female | 1.234 | 1.306 | 1.351 | 1.414 | 1.476 | |
| 75-79 | Male | 1.278 | 1.346 | 1.396 | 1.442 | 1.512 |
| Female | 1.219 | 1.298 | 1.351 | 1.413 | 1.499 | |
| 80+ | Male | 1.278 | 1.350 | 1.397 | 1.440 | 1.509 |
| Female | 1.227 | 1.313 | 1.362 | 1.421 | 1.497 | |
What to expect by age group
Among US adults, median Conicity Index runs from about 1.22 in young adults to roughly 1.40 in the oldest bracket, trending upward with age. Men record higher Conicity than women in nearly every bracket. Conicity uses a distribution scale (Very low to Very high) rather than good-to-bad performance labels, because it is a body-shape distribution rather than a fitness test; higher values do indicate more central adiposity.
| Age | Males | Females |
|---|---|---|
| 20-24 | 1.170 to 1.296 | 1.169 to 1.290 |
| 25-29 | 1.190 to 1.310 | 1.190 to 1.319 |
| 30-34 | 1.226 to 1.339 | 1.206 to 1.342 |
| 35-39 | 1.247 to 1.348 | 1.223 to 1.348 |
| 40-44 | 1.264 to 1.351 | 1.233 to 1.348 |
| 45-49 | 1.272 to 1.362 | 1.228 to 1.358 |
| 50-54 | 1.286 to 1.375 | 1.258 to 1.373 |
| 55-59 | 1.297 to 1.390 | 1.270 to 1.384 |
| 60-64 | 1.304 to 1.412 | 1.280 to 1.389 |
| 65-69 | 1.315 to 1.412 | 1.288 to 1.411 |
| 70-74 | 1.339 to 1.429 | 1.306 to 1.414 |
| 75-79 | 1.346 to 1.442 | 1.298 to 1.413 |
| 80+ | 1.350 to 1.440 | 1.313 to 1.421 |
Detailed Breakdowns
Select an age group and sex below for detailed percentile charts and distribution labels.
Frequently Asked Questions
What is a normal Conicity Index?
Among US adults, the median Conicity Index is roughly 1.2 to 1.4 depending on age and sex, with men slightly higher than women. The full percentile tables on this page show where any value sits within an age and sex group.
How is Conicity Index different from waist-to-height ratio?
Both use the waist, but Conicity Index also factors in body weight: it compares your waist to the circumference of a cylinder with the same weight and height (Valdez 1991), whereas waist-to-height ratio is simply waist divided by height. Conicity is reported on a shape-index scale around 1.1 to 1.5 rather than a 0-1 ratio.
Why do these percentiles use a Very low to Very high scale?
Conicity Index is a body-shape distribution, not a fitness test. There is no single agreed clinical cut-off (published thresholds vary by study and outcome), so we show where a value sits in the population distribution rather than labelling it good or bad.
Why might these values seem high?
These percentiles come from US adults (NHANES), a population with a measured adult obesity rate of 42.4% by BMI (Hales et al. 2020). Conicity Index rises with central fat, so in a leaner population the same value would be expected to rank higher. We did not find a directly comparable non-US Conicity percentile table to put an exact figure on that difference, so we describe the direction rather than a magnitude.