Figuring the body fat percentage of you or your clients can be tricky. Sure, you can use images, calipers, or a something more accurate like a Bod Pod or hydrostatic test, but sometimes you need a way to figure it out on the fly. In this case, you can use the simplified charts that I created below.

Semi-Scientific Methodology

First off, take these with a grain of salt. They’re based on a few hundred data points that I had from men and women, for whom I had waist measurements and a reasonable guess about their body fat percentage.

A Gompertz curve did a pretty good job predicting body fat percentage when plotted against waist measurement, so I used the data points to create a rather unwieldy function, then spat it out into two tables for ease of reading.

While there are obviously cases that don’t fit, the lookup tables have been surprisingly accurate. Try it for yourself.

Lookup Table for Men

Waist (inches)	Approximate Bodyfat Percentage
25	5%
26	6%
27	7%
28	8%
29	9%
30	10%
31	11%
32	13%
33	15%
34	17%
35	19%
36	21%
37	23%
38	26%
39	29%
40	31%
41	34%
42	36%
43	39%
44	42%
45	44%
46	46%
47	48%
48	50%
49	52%
50	54%

Lookup Table for Women

Waist (inches)	Approximate Bodyfat Percentage
25	15%
26	15%
27	16%
28	17%
29	18%
30	21%
31	23%
32	26%
33	28%
34	31%
35	34%
36	37%
37	40%
38	43%
39	46%
40	48%
41	51%
42	53%
43	56%
44	58%
45	60%
46	62%
47	63%
48	65%
49	66%
50	67%