true, there are ways to get a good estimate of your body fat % by going off of measurements. but those with larger skeletal frames will show up as a higher %, basically the same problems faced by BMI calculations.
Still, it'd be a reasonable estimate...so you'd know if you were in the upper teens, or lower, etc...
Calipers aren't perfect, but are better than those bio-impedience meters, a.k.a. the Tanita brand scales. And of course, the underwater body fat test is supreme, but I heard it costs $1,000 for normal people (non-olympic athletes) to get tested, and it's not a real common testing device, so good luck finding one.