To measure your penis accurately, you need a ruler or flexible measuring tape, a full erection, and a consistent technique. The standard approach is to measure along the top of the shaft, from the base to the tip, while standing. Getting a reliable number takes a little more care than most people expect, so here’s exactly how to do it.
How to Measure Length
Stand upright with a full erection. Place a ruler or rigid measuring tape along the top of your penis, pressing the end gently but firmly into the pubic bone at the base. This is called the “bone-pressed” method, and it’s the standard used in medical research because it removes the variable of body fat covering the base. Measure in a straight line from the pubic bone to the very tip of the head.
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 base to tip. A rigid ruler held against a curved shaft will give you a shorter reading than your actual length.
You may also see references to “non-bone-pressed” length, which is the same measurement without pressing into the pubic bone. This number will be shorter, especially if you carry extra weight around your midsection. Most published averages use the bone-pressed method, so that’s the one to use if you’re comparing.
How to Measure Girth
Girth is the circumference of the shaft. Wrap a flexible measuring tape snugly around the thickest part of the shaft, typically just below the head, while fully erect. Read the number where the tape meets itself. Don’t pull the tape tight enough to compress the skin, and be cautious with stretchy fabric tapes, which can overestimate if pulled hard.
If you don’t have a measuring tape, wrap a piece of string or a strip of paper around the shaft, mark where it overlaps, then lay it flat against a ruler to get your circumference.
Getting a Consistent Reading
Several things can change your measurement from one session to the next. Arousal level matters most: you need a full, stable erection each time. Partial erections will give you a shorter, thinner result. Room temperature also plays a role because cold causes blood to redirect away from the genitals. Stress and anxiety trigger a similar response, as adrenaline pulls blood flow toward the core. For the most reliable number, measure on a few different occasions when you’re relaxed and warm, then take the average.
Always measure from the top of the shaft, not the side or the underside. Measuring from the side angles the ruler and adds length. Measuring from the underside includes the scrotum-to-shaft junction, which inflates the number. The top-center line, pressed to the pubic bone, is the only position that gives a standardized result.
The Stretched Flaccid Method
Urologists often skip the erect measurement entirely and instead use stretched penile length. This is the technique used before procedures like implant surgery because it closely approximates erect size without requiring an erection in a clinical setting. To do it yourself: press one hand flat against the area above the base of your penis, retract the foreskin if applicable, then gently grip the head between your thumb and forefinger and extend the penis forward until it’s fully stretched but not uncomfortable. Measure from the pubic bone to the tip.
A large meta-analysis covering over 15,500 men found that the average stretched flaccid length was 13.24 cm (5.21 inches), while the average erect length was 13.12 cm (5.16 inches). The two numbers are remarkably close, which is why clinicians consider the stretched method a reliable stand-in.
How You Compare to Averages
That same analysis, published in BJU International and covering 17 studies with measurements taken by healthcare professionals, found the following averages:
- Flaccid length: 9.16 cm (3.61 inches)
- Erect length: 13.12 cm (5.16 inches)
- Flaccid girth: 9.31 cm (3.66 inches)
- Erect girth: 11.66 cm (4.59 inches)
These numbers come from clinician-measured data, not self-reported surveys, which tend to skew higher. If your result is in the general neighborhood of these figures, you’re well within the normal range. A true micropenis is defined as a stretched length more than 2.5 standard deviations below the mean for age, which is an extremely rare diagnosis.
Why Your Number Might Bother You Anyway
Even among men with average measurements, dissatisfaction is surprisingly common. Research shows that about 45% of men say they’d prefer a larger penis, while 84% of women report being satisfied with their partner’s size. That gap suggests the anxiety is largely internal rather than driven by a partner’s experience.
Clinicians recognize a pattern called small penis anxiety, where someone with a normal-sized penis experiences ongoing distress about their size. In about 10% of men, a negative perception of their size affects sexual function and quality of life. In more severe cases, this can overlap with body dysmorphic disorder, a condition where a perceived flaw that others can’t see causes significant emotional suffering. If measuring yourself is driven by persistent worry rather than curiosity, that pattern is worth paying attention to on its own.