Apps are really bad at figuring that kind of thing out. In fact, so are insurance companies, and gyms, and so on.
The only real way is to get an expensive, medical test.
Several cases in point.
According to our health insurance company, my husband who is 6' tall and is 175, falls in the same obese category as his boss, who is 5'8", and weighs 300 pounds.
According to my son's employer, he is a state trooper, at 5'11", 180, he is also obese. You could wash you clothes on his abs, knock out elephants with his thighs, if you held them as a club, and at 35 he can still run a 5 second 40.
Me, our insurance, I am 58, 140 pounds, lift a lot, work for a veterinarian, a physical job, they told me I was fat. After I held their little gizmo.
Quit worrying about focusing on that stuff, focus on good health, embrace what you have, love it, and make the best you, you can be!