The penis is a cylindrical organ made up of a few distinct parts: a shaft, a head (called the glans), and an opening at the tip where urine and semen exit. Beyond that basic structure, there’s a wide range of normal when it comes to size, shape, skin color, and curvature. Here’s what each part looks like and what variations you can expect.
Basic External Anatomy
The shaft is the longest part of the penis, extending from the pelvis to the tip. It’s soft and flexible when flaccid and becomes rigid during an erection as internal tissue fills with blood. The skin along the shaft is relatively loose, allowing it to stretch during erection, and visible veins running along the surface are completely normal.
At the end of the shaft sits the glans, or head. The glans is typically smoother and slightly wider than the shaft, with a ridge along its base called the corona. This ridge creates a subtle mushroom-like shape. The glans also fills with blood during arousal, which can make it appear darker or more flushed. At the very tip of the glans is a small slit-like opening called the meatus, where urine and semen exit the body.
Circumcised vs. Uncircumcised
One of the most noticeable visual differences between penises is whether the foreskin is present. The foreskin (or prepuce) is a retractable hood of skin that covers the glans. In an uncircumcised penis, the glans is partially or fully covered when flaccid, and the foreskin slides back during an erection or can be pulled back manually. A circumcised penis has had this skin removed, so the glans is always exposed. The glans of a circumcised penis often appears slightly drier or more textured over time compared to an uncircumcised one, where the glans stays more moist and smooth beneath the foreskin.
On the underside of the glans, there’s a small V-shaped area of sensitive tissue called the frenulum. In circumcised penises, some or all of this tissue may have been removed, while it’s typically intact in uncircumcised penises. Both variations are normal and functional.
Average Size
A study of over 15,000 men found that the average flaccid penis is about 3.6 inches long with a circumference of 3.7 inches. When erect, the average length is 5.1 inches with a circumference of 4.5 inches. These are averages, and healthy penises fall across a broad range above and below these numbers. A penis that appears small when flaccid may grow significantly during erection (sometimes called a “grower”), while others stay closer to their flaccid size (a “shower”). Both patterns are normal.
Skin Color and Texture
The skin of the penis is often darker than the surrounding body, even in people with lighter skin tones. This hyperpigmentation is caused by higher concentrations of melanin in genital skin and is entirely normal. The degree of darkening varies from person to person. Some penises are fairly uniform in color, while others have noticeable differences between the shaft and glans or patches of lighter and darker skin.
The texture of penile skin also varies. The shaft skin is thinner than skin elsewhere on the body, which is why veins are often visible beneath the surface. Small, painless bumps are common and usually harmless. Pearly penile papules, for example, are tiny dome-shaped or finger-like growths that appear in rows around the corona (the ridge of the glans). They look like small white, yellow, or pink spots, each roughly 1 to 2 millimeters wide. Somewhere between 14% and 48% of males have them at some point. They’re not an infection or STI, and they don’t require treatment.
Another common finding is Fordyce spots, which are small, pale or yellowish raised dots on the shaft or foreskin. These are simply visible oil glands and appear on many people’s genitals and lips. Neither pearly penile papules nor Fordyce spots are contagious or harmful.
Curvature and Shape
Very few erect penises point perfectly straight. A slight curve to the left, right, up, or down is normal and doesn’t affect function. The direction and degree of curvature varies from person to person and is determined by the internal structure of the tissue.
Curvature becomes a medical concern only when it’s significant enough to cause pain or make intercourse difficult. Peyronie’s disease involves the buildup of scar tissue (plaque) inside the penis that creates a more pronounced bend, typically greater than 30 degrees. This condition can develop after injury or over time. If the curve is mild, painless, and doesn’t interfere with sex, treatment usually isn’t needed.
The Scrotum and Testicles
Below the penis hangs the scrotum, a pouch of skin containing the two testicles. Scrotal skin is typically darker than the surrounding area, thinner, and wrinkled. It tightens and draws the testicles closer to the body in cold temperatures or during arousal, and hangs lower and looser in warm conditions. This is the cremaster muscle at work, regulating temperature to protect sperm production.
It’s normal for one testicle to hang lower than the other. The left testicle is lower in most men because its blood drains through a longer path. This staggered positioning actually serves a purpose: it prevents the testicles from pressing against each other. One testicle being slightly larger than the other is also common and rarely a concern.
Changes During Puberty
Before puberty, the penis and testicles are small and proportional to the rest of the body. Around age 11 or 12, the testicles typically begin to enlarge first, followed by lengthening and thickening of the penis. Pubic hair appears and gradually becomes coarser. The penis generally reaches its mature size by around age 16 to 17, though the timeline varies. During this period, the skin of the genitals also darkens, and the scrotum develops its characteristic texture.
Changes With Age
The appearance of the penis shifts gradually over the decades. As blood flow decreases due to natural arterial changes, the glans can become lighter in color. The skin of the shaft and scrotum may lose some elasticity, appearing looser or thinner. Weight gain around the abdomen can also bury part of the base of the shaft in a fat pad, making the penis appear shorter than it actually is, even though the internal structure hasn’t changed. Pubic hair thins and may turn gray, just like hair elsewhere on the body.