Open Question: How do I determine body frame size?

I have lost alot of weight. I am about 5'8.5". I weigh 178 lbs. I read these calculators and they all say I am pretty over weight, about 20 lbs, but I actually look pretty good. I have pecs starting to form and abs as well. I feel like I just need to tone my body and I will look great. When I look at these calculators they say you can add 10% for a large frame or subtract 10% for a small