I saw a youtube comment today, “Speaking from an anatomical point of view, it wouldn’t matter, as no human is even close in length to a horse penis. So tap it or not, she’s gonna be one extremely disappointed pony, as would all the ponies in that show.”, and my immediate reaction was disagreement: MLP ponies are not NEARLY as tall as real horses, so their penises will be proportionally smaller as well.

So I did some math, to try and settle the great debate of our age.

Based on what I’ve read, a riding horse of about 16 hands in height will have a penis roughly 12-18 inches in length. I’ve heard numbers up to 22 inches, so we’ll go with “18” as a rough estimate of “average”, just to be on the safe side.

A MLP:FiM pony is about 3.5 feet tall at the top of the head, up to 4 feet at the top of the hair.

However, a horse is not measured to the top of the head: they are measured to the withers, in hands. This is actually convenient, because the size of the penis is proportional to the size of the body, not the head, and the head of a MLP is disproportionately gigantic in comparison to their body. So we can use a measurement to the withers to get a pretty good guess as to the penis size.

A 3.5 ft MLP’s withers are at only about 60% of their total height. 3.5 feet is 10.5 hands. 60% of 10.5 is 6.3. So a MLP is roughly 6.3 hands tall, in comparison to a 16 hand tall medium sized riding horse. 6.3/16 = about .39, meaning a MLP’s body is roughly 40% the height of a typical horse’s body.

And, finally, 40% of 18 inches is 7.2 inches.

So, there we have it. The average MLP penis is something around 7 inches. This is non-trivially larger than the average human penis, but certainly not larger than what many men actually have in size. Other than anatomical estimations, one other obvious flaw here is that some ponies, like Big Mac, are larger than the typical pony.