The average erect penis is about 5.1 inches (13.12 cm) long and 4.5 inches (11.66 cm) around. If your measurements are above those numbers, you’re larger than most men. But getting a reliable answer starts with measuring correctly, since most guys have never done it the way researchers do.
How to Measure Correctly
Grab a ruler or measuring tape and wait until you’re fully erect. Place the ruler on top of your penis, right where the shaft meets your body at the pubic bone. Press the end of the ruler firmly into the pubic bone, pushing past any fat pad or pubic hair. Then measure in a straight line from that point to the tip. This is called a “bone-pressed” measurement, and it’s the standard used in virtually every clinical study. If you skip the pressing step, you’ll get a shorter number that doesn’t match the research data, making any comparison unreliable.
If your penis has a noticeable curve, use a flexible measuring tape instead of a rigid ruler. Lay the tape along the top surface, following the curve, from pubic bone to tip.
For girth, wrap a measuring tape or a strip of paper around the thickest part of the shaft while erect. If you used paper, mark where it overlaps and then measure that length flat. That’s your circumference.
What the Averages Actually Are
A large review combining data from over 15,000 men, conducted by researchers at King’s College London, found these averages:
- Erect length: 5.16 inches (13.12 cm)
- Erect circumference: 4.59 inches (11.66 cm)
- Flaccid length: 3.61 inches (9.16 cm)
- Flaccid circumference: 3.66 inches (9.31 cm)
If your erect length is above 5.5 inches, you’re comfortably above average. At 6 inches or more, you’re larger than a clear majority of men. For girth, anything over 5 inches puts you above the norm. These numbers cluster tightly around the mean, so even half an inch in either direction makes a real difference in where you fall relative to everyone else.
Flaccid Size Doesn’t Tell You Much
Some penises grow dramatically during an erection. Others stay close to their flaccid size. Researchers have actually studied this distinction. In one study of 274 men, the average gain from flaccid to erect was about 1.6 inches (4 cm). Men who gained more than that were classified as “growers,” and those who gained less were “showers.” About 74% of men fell into the shower category, while 26% were growers.
This means your soft size is a poor predictor of your erect size. If you’ve been comparing yourself to other men in locker rooms or casual situations, that comparison is essentially meaningless. Two men with very different flaccid sizes can end up nearly identical when erect, or vice versa.
Length vs. Girth: What Matters More
Men tend to fixate on length, but girth plays a bigger role in how size is experienced during sex. In one study, only 21% of women rated length as important, while 33% rated girth as important. This makes anatomical sense: the outer portion of the vaginal canal has far more nerve endings than the deeper portion, so width creates more sensation than depth for most partners.
That said, the broader picture is more important than either dimension alone. In a large survey published in the APA’s Psychology of Men & Masculinity, 84% of women said they were satisfied with their partner’s penis size. Most women (67%) described their partner as average, and 27% described their partner as large. Among those two groups, satisfaction rates were 86% and 94% respectively. Only 6% of women perceived their partner as small, and within that group, 68% wished their partner were larger.
Why Your Perception May Be Off
There’s a consistent gap between how men see themselves and how their partners see them. In the same research, only 55% of men were satisfied with their own penis size, compared to 84% of their female partners who were satisfied with it. That’s a massive disconnect. Nearly half of men feel inadequate about something their partners are perfectly happy with.
Part of the distortion comes from perspective. You look down at your own penis from above, which foreshortens it visually. You never see it from the angle a partner does. Pornography creates additional distortion: performers are selected specifically for being outliers, camera angles exaggerate size, and shorter performers are sometimes cast alongside them to amplify the effect. Comparing yourself to porn is like watching the NBA and concluding you’re short.
Putting the Numbers in Context
If you measured correctly and you’re at or above 5.1 inches in length and 4.5 inches in girth, you’re average or bigger. If you’re above 6 inches long and 5 inches around, most people would consider that big. The reality is that the vast majority of men fall in a surprisingly narrow range, and size alone is a weak predictor of sexual satisfaction for either partner. Technique, communication, arousal, and comfort level all carry more weight in how sex actually feels.