I was really unsure where to put this thread as it didnt match any criteria apart from General discussion, but seeing as though its a science or theory I will put it here but mods feel very free to move it.
I came across a way to check BF% called the Navy formula, I tested it on myself and my cousin we both have different builds and he also had a caliper test done that week and for him on that instance the navy formula proved to be almost identical(within 1%) to the caliper test.
What you do is measure the circumference of your neck below your adam's apple, and measure your waist along your belly button, input your height and it gives you your BF%.
The link I have included has input for weight and activity level but these are not for the BF% part but for the BMR part which is something else, so you can disregard those fields and input whatever numbers you like. Women have a different formula and I am not sure of its accuracy.
Diet Calculator, Body Fat Calculator