Calculate your % Body Fat

[Nelson Longflap]

That formula gives me 18% fat. The US navy one works out at 14%. BMI 21.6.

I'd say those numbers are probably much the same within the probable margins of error (that we still don't know).  So you might with some confidence say your %bf is 16% +/- 2% 

[Asterix, the former Gaul.]

Have never tested my body fat.  According to the method I got 40%

Then I read the instructions properly and got 18%

According to some tables that is simply average!  But it is better than 40%!  I am glad I got it wrong the first time, it softened the blow.

[arabella]

hahahahahha.
It gave me less than 15%.
I carry so much lard I float.

No, it must be muscle - I'm 20% so you do indeed have an inner hulk of muscle. 
Obv. I have been eating too many choc bics.