Penis Facts

How The Penis First Forms

Men have the advantage of getting pretty familiar with their penis as their genitals are right out in the open. Unlike women who need a mirror and a yoga position, the penis is a very accessible organ to men. You might not think so from looking, but the male and female sex organs have a lot in common. Did you know that in the womb, we all start as a biological female?

We All Begin As Female

Females are the platform of the human species, and males are a chromosomal mutation. We all start as the X chromosome. If another X is added, we remain a biological female; if a Y is added, our development changes to a biological male and our female organs are transformed into a male.

On the backside of a penis are the remnants of a man's vagina when his male sex was not yet determined and had female organs in early gestation. In addition, the highly sensitive spot on the back of a man's penis, where the foreskin attaches, was the female clitoris.

Here are the equivalent genital comparisons from female to male.

• Clitoris = Head (Glans) Of The Penis
• Clitoral Hood = Foreskin
• Clitoral Legs = The Shaft Of The Penis
• Female Prostate = Male Prostate
• Ovaries = Testicles
• Fallopian Tubes = Appendix Testis
• Uterus, Cervix, Vagina = Prostatic Utricle
• Labia Majora = Scrotum
• Labia Minora = Penile skin

Chromosomes

We each have 23 pairs of chromosomes. The last pair are known as the sex chromosomes. Typically, a person will have either an XX or XY pair of sex chromosomes. Intersex is when there is a discrepancy between the external genitals and the internal genitals (the testes and ovaries). There are four types as shown below.

• 46, XX Intersex: This is when a person is born with the chromosomes and ovaries of a woman but has a penis and testicles.
  
  
• 46, XY Intersex: This is when a person is born with the chromosomes of a male, but the genitals are not entirely formed, ambiguous, or is a vulva.
  
  
• True Gonadal Intersex: This is when a person is born with both ovarian and testicular tissue and may have XX chromosomes, XY chromosomes, or both.
  
  
• Complex Or Undetermined Intersex: This is a catchall for other chromosome combinations such as 45, XO (only one X chromosome), and 47, XXY, 47, XXX, which in both cases have an extra sex chromosome of an X or a Y.

It is important to note that sometimes people do not identify with their chromosomes' biological sex and are transgender. Please see our LGBT+ Guide for more information.

Penis Anatomy

Corona
The ridge of flesh demarcating where the head of the penis and the shaft join.

Frenum
Frenulum A thin strip of flesh on the underside of the penis that connects the shaft to the head.

Foreskin
Prepuce A roll of skin which covers the head of the penis in uncircumcised men.

Urethra
Meatus Opening at the tip of the penis to allow the passage of both urine and semen. The Shaft Area from the corona to the scrotum.

Scrotum
A sac that hangs behind and below the penis and contains the testes, the male sexual glands. The scrotum's primary function is to maintain the testes at approximately 93.2 degrees Fahrenheit (34 C), the temperature at which the testes most effectively produce sperm.

Prostate
Produces a fluid that makes up the semen. The prostate gland also squeezes shut the urethra duct to the bladder, thus preventing urine from mixing with the semen. Learn more about the prostate through our Prostate Massage Guide and our helpful guide on Enlarged Prostate Solutions (BPH). 

What Happens When A Penis Becomes Erect

When sexual arousal occurs, the nerves begin to stimulate the penis. The brain receives impulses that cause the muscles of the corpora cavernosa to relax. This allows blood to fill open spaces in the penis. The pressure is then created in the corpora cavernosa, making the penis expand, creating an erection.

Urinating & Erections

When a penis is erect, the sphincter (located at the base of his bladder) will close. This means that urine will not pass into the urethra. That is why men will not be able to urinate when erect and during sex. Most men will say that it is almost painful to try when they are even partially erect.

If a man finds it difficult to urinate after sex, the best way to achieve urination is to relax as that will also relax the sphincter muscle. In addition, instead of pushing the urine out while standing, bend over to urinate or sit down. You can also massage your bladder (between you navel and pubic bone) to relax it. If you continue to have an issue urinating after an erection, try using a hot water bottle or heating pad on your bladder to relax your muscles.

If you continue to have a problem urinating, you may need to consult with a physician, especially if you have a fever, chills, lower back pain, or vomiting.

Circumcision

Circumcision is the surgical removal of the sleeve of skin and mucosal tissue that usually covers the glans (head) of the penis. This double layer, sometimes called the prepuce, is more commonly known as the foreskin. See our Guide On Circumcision for more information. 

Penis Size

A study found in The British Journal of Urology measured 15,521 different men and found that the average length of a flaccid penis is 3.6 inches (9.16 cm). In contrast, the average length of an erect penis is 5.2 inches (13.12 cm). The average girth is 3.7 inches (9.31 cm) when flaccid, while the average erect circumference was 4.6 inches (11.66 cm).

How To Measure The Penis

After obtaining an erection, angle your penis down until it is parallel to the floor. Set your ruler against your pubic bone just above the penis base and measure to the tip. Also see our Penis Enlargement Guide. 

Penis Facts

• A large penis is anything over 7 inches in length when erect and anything more than the 4.59 average girth.
  
  
• The average erect penis is about 5.56 inches (14 cm) long.
  
  
• There is no correlation between the length of a flaccid penis and its erect size. A penis can start small and end up larger (a grower), while some penises are large when flaccid and only grow a little when erect (a show-er).
  
  
• Penis size may be correlated with age, height, and index finger length, but not foot size.
  
  
• A man's penis is penises are longer than they look as half of its entire length inside the body.
  
  
• Erections can happen 3-5 times per night while a man sleeps.
  
  
• The most dangerous sex position for breaking a man's penis (penile fracture) is his partner riding him from on top. Luckily if it is medically treated right away, it can usually be restored.
  
  
• The average length of the penis when not erect: 3.5 inches.
  
  
• Average length when erect: 5.2 - 6.4 inches.
  
  
• The longest human penis: 13.5 inches (9.5 inches or 24 cm in length when flaccid). 
  
  
• The widest human penis: 6.25 inches (16 cm) in circumference.
  
  
• The smallest human penis: 5/8 of an inch.
  
  
• The largest penis in the animal kingdom: 11 feet (blue whale).
  
  
• The actual amount of semen per ejaculation: 1-2 teaspoons.
  
  
• The average number of times a man will ejaculate in his lifetime: 7,200
  
  
• The average number of times a man will ejaculate from masturbation: 2,000
  
  
• The average total amount of lifetime ejaculate: 14 gallons.
  
  
• The average speed of ejaculation: 28 miles per hour.
  
  
• The average number of calories in a teaspoon of semen: 7
  
  
• Most arousing time of day/season for a man: early morning/fall
  
  
• Best ways to improve sexual function: quit smoking, start exercising, lose weight.
  
  
• Percent of men who say they masturbate: 60%
  
  
• Percent of men who say they masturbate at least once a day: 54%
  
  
• Percent of men who say they feel guilty masturbating that often: 41%
  
  
• Amount of time needed for a man to regain erection: from 2 min to 2 weeks
  
  
• The average number of erections per day for a man: 11
  
  
• The average number of erections during the night: 9
  
  
• Sperm life: 2 1/2 months (from development to ejaculation)
  
  
• The thickness of the average condom: .07 mm
  
  
• The thickness of super-thin condoms: .05 mm
  
  
• The speed at which erotic sensations travel from skin to brain: 156 miles per hour
  
  
• Calories in a teaspoon of semen: 5
  
  
• All penises bend slightly to the left or right.
  
  
• Odors increase blood flow to the penis: lavender, licorice, chocolate, doughnuts, and pumpkin pie.
  
  
• The Caramoja tribe of northern Uganda tie a weight on the end of their penises to elongate them, sometimes to such a degree that the men have to knot them up.
  
  
• The Mambas of New Hebrides wrap their penis in yards and yards of cloth, making them look up to 17 inches long. Many other cultures do this.
  
  
• In 1609, a doctor named Wecker found a corpse in Bologna with two penises. Since then, there have been eighty documented cases of men similarly endowed.
  
  
• When men of the Walibri tribe of central Australia greet each other, they shake penises instead of hands.
  
  
• In America, hundreds of thousands of circumcised foreskins have been sold to bio-research laboratories.

See Related Articles

• Sex Toys For Erectile Dysfunction
  
  
• Peyronie's Disease: Natural Treatments
  
  
• Natural Erectile Dysfunction Remedies
  
  
• STDs & Prevention

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