When Does a Penis Stop Growing? Later Than You Think.

If a boy is still growing, his penis is probably still growing too.

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A phallic cucumber grows on the vine

First of all, it doesn’t matter how big it is. Parents should broadcast this to teenage boys and check themselves if they’re wondering how well-endowed their toddler will be. A big or small penis does not guarantee happiness or a lack thereof. Besides, when it comes to sex, penis proportions matter far more than size (but, maybe hold off on that fact until they’re in their twenties). That said, many still wonder how big it will be and find themselves asking “when does a penis stop growing?” The answer depends on a child’s personal puberty trajectory, according to Judson Brandeis, MD, a board-certified urologist in San Francisco, California.

When Does a Penis Stop Growing?

The penis goes through its most rapid growth spurt during puberty as a result of a testosterone boost. Most growth occurs between the ages of 12 and 16. But that doesn’t always mean a kid has hit their peak by that point. Some boys experience puberty and additional penis growth into adulthood. For most, it stops at age 18. But some men, though few in number, report experiencing growth in their penis size into their early 20s.

“The penis begins growing when a boy reaches puberty and his testosterone levels begin to spike. The penis achieves its full length and girth at the end of puberty,” Brandeis says. The testicles start growing much earlier, at around 8 years old, also continuing until the end of puberty, he adds.

Penis growth starts in the early teens, and most men reach their penis potential in both length and girth at around the same time they hit their height peak. So late bloomers can hold hope that the best is yet to come.

One factor that can determine how long a boy’s penis will grow is his weight, according to a new study of 1,130 boys. The researchers found that boys with obesity had lower testosterone than boys of a typical weight, and the former had about 10 percent less penile length growth.

What’s the Average Penis Size?

Let’s get right to the thick of it: The average penis size is somewhere between 5.1 and 5.5 inches erect, although the real number is probably toward the lower end of that range, according to a review study. The average girth is around 4.59 inches erect, according to another review study.

For years, research has shown that the average penis size was 6.2 inches erect. But it turns out that in much of the research, men had been exaggerating their lengths so often that it led to this common misconception. When researchers began to measure the penis size themselves instead of just asking, the numbers skewed downward. In fact, it’s likely that less than 12 percent of penises are longer than 6.3 inches erect.

And those old wives’ tales about the link between penis size and the size of hands and feet? Not surprisingly, they’re complete bullshit. The length of your ring finger may be a better measure. Or maybe even your nose size.

The Ideal Penis Size for Performance

Men often think their penises are smaller than average. And whether or not that’s true, this perception can make them overly self-conscious.

But if you’re worried about how a smaller-than-average penis affects your game in the bedroom, you can relax. In a survey of 52,031 men and women, 85 percent of partners reported being satisfied with their man’s penis size while only 55 percent of men thought their penis was large enough. The bottom line: Most men need to be a little more proud of what they’re packing.

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