It’s common for people with penises to wonder if their penis size is normal, and if their penis will keep growing. According to health experts, the average person’s penis will stop growing once they’ve finished puberty, around age 18.‍

Penis growth guide and timeline‍

A 2010 study published in the Archives of Pediatrics & Adolescent Medicine found peak growth happens between ages 12 and 16. Penises grow an average of a half inch per year between ages 11 and 15, and then less per year after that,That said, every body is different so growth and size varies from person to person.

“A person's penis will begin growing during puberty,” sex educator Dan Rice, M.Ed.tells O.school. “Puberty is a time when people's bodies start to change and develop into adults. This typically happens between the ages of 11 and 15 and lasts for about five to seven years. This means there's not one exact age all penises hit their full size. For some people, it may be earlier, and for other people it may be later. Either way, it's normal.”

The penis won’t necessarily start growing exactly when you hit puberty, Rice adds, and it may not necessarily continue to grow for the full five to seven years when the rest of your body is growing.  And “similar to the fact that there is not one exact age that all penises hit their full size, there is no exact length a person can expect to see their penis grow,” Rice says.

Once it hits its full size, your penis will pretty much stay the same size for the rest of your life. Board-certified urologist Jamin Brahmbhatt, M.D., adds that sometimes weight gain can obscure the penis a bit, though it won’t actually get smaller and for some it may decrease in size a bit in old age.‍

What’s the average penis size?‍

The average penis size is around 3.5 inches flaccid (soft) and around 5.1 inches erect, Dr. Brahmbhatt tells O.school.

“Most guys are just fine in terms of size and girth,” he says. “But when they size themselves up against the adult film industry, they may start having insecurities. You should NOT size yourself up to porn — a lot of it is not reality.”

“There is no such thing as a penis that is too small,” board-certified urologist Elizabeth Kavaler, M.D., tells O.school.‍

Can you make your penis bigger?‍

There’s a whole market of devices, supplements, and surgeries that say they can increase penis size, but there’s little to no science behind these claims.

“The procedures you see online (stretch tools, fillers, penile exercises) don’t have much clinical backing,” Dr. Brahmbhatt explains. “But guys still do it in hopes of gaining that inch or two — most of the time, they may be putting their penis at risk from scarring.”

“The size of a person's penis is determined by genetics—just like eye color, hair color, how tall a person grows, and all our other physical features,” Rice says.

Trying to change the size of your penis may damage its normal functioning, Dr. Kavaler warns: “All of the options have a significant downside. For the penis to function effectively and happily, an interplay exists between blood flow, tissue integrity, hormonal balance, and mental health. Surgery, devices, pumps, and pills can impact negatively on any or all of these factors. The penis is a functional organ, much like the heart. Appreciating what you have, if it works well, is the safest approach.”‍

Does penis size matter?‍

The short answer? No. People who sleep with individuals with penises have all kinds of preferences, and not everyone enjoys giant penises. A bigger penis also doesn’t necessarily make you a better partner or give your partners more physical pleasure.

“Size alone has never determined whether someone was a good person, a good partner, [or whether] we’re good at anything for that matter,” AASECT-certified sex educator Logan Levkoff, Ph.D., tells O.school. “It’s not really about size. It’s about how you use what you have and whether or not you listen to what [your] partners need.”

Penis size might affect men’s confidence more than it actually affects how attractive they are or how sexually satisfied their partners are. A 2006 study of over 50,000 heterosexual men and women published in the Psychology of Men & Masculinity journal found the vast majority of women (85 percent) were totally satisfied with their partner’s penis size, compared to just 55 percent  of men who felt satisfied with their own penis size. Dr. Brahmbhatt says dispelling myths about the importance of penis size and working on building sexual confidence can sometimes be the best way to address the men’s concerns about size.

If you’re concerned nonetheless (or perhaps unsure if your penis has stopped growing), Dr. Kavaler recommends seeing a urologist (or your healthcare provider) to get a medical opinion. More likely than not, you’re probably fine.