IF I remember correctly from statistics and if you're looking at the calcSD website, with an average of 5.64" and a standard deviation of only 0.74", (assuming a standard bell curve), 68% of men should fall within 4.9" and 6.38" and a whopping 95% would fall within the range of 4.16" and 7.12", only a 2.96" spread which is a pretty narrow range if you ask me. Only about an inch and a half either direction of middle.
I too was WAAAAY skeptical of these numbers because I've only ever had porn as a reference so since being on the forum I've done a bit of research and it seems just about EVERY study ever conducted puts the average in, at, or around the 5-5.5" mark with a standard deviation of 3/4" -7/8" inch, pretty consistent if you ask me, whether it's a study of 80 men, or nearly 2000.
So yea, with the 95th percentile topping out at 7.12", I can believe that most porn stars hit the 7-8" mark making them a true rarity, add small actresses, minimal body fat and camera tricks and voila, male body dysmorphic disorder. I can also (well starting too anyway) believe that my 6.5" length that puts me in the 87th%-tile and my 5.5" girth putting me in the 91st%-tile is pretty close to reality, even though I have no real life testimony. I think there is also a common mindset/personality trait that has brought us to this forum and those of us here being slightly above average to significantly above average puts the mean of this forum into a different subset, kind of like the subset on calcSD called /r/BDP. Also keep in mind that that last 5%, the 95th%-tile plus, could represent over 140 million penis' over 7". With that many, it's easy to find a handful of porn stars and a few Reddit pictures of huge penises; but still those are only 5% to less than 5% of the entire population.