concave, as in pregnancy and obesity, the waist may be measured at a vertical level 1 inch above the navel. Some laypersons use the level at the navel, but this can lead to underestimates.

When using an automated body scanner that produces a point cloud, neither the bones nor the navel can be located from the scan itself. A commonly used definition is the circumference at 4 cm above small of the back (SOB), though this does not appear to be the best fit