Penis Size Percentile Calculator

Enter your erect length, girth, or both, in inches or centimeters, and we compare them against clinician-measured data from up to 15,521 men to show where you fall in the real distribution.

A quick word before the numbers, because we know why most people are on this page. Nearly everyone who measures themselves against the internet's numbers comes away feeling below average. That's not biology; it's bad data. The figures that circulate online come from self-reported surveys, and men round up. The clinical numbers on this page come from studies where a researcher did the measuring, and they are smaller than what you've heard. Wherever you land on this chart, you're in a distribution of 15,500 ordinary men. Normal is a much wider place than the internet makes it look.

Enter either measurement or both. Nothing you type is stored; the math runs entirely in your browser.

How the percentile calculator works

Every number on this page traces to one source: Veale, Miles, Bramley, Muir, and Hodsoll, "Am I normal? A systematic review and construction of nomograms for flaccid and erect penis length and circumference in up to 15,521 men," BJU International 2015;115(6):978-986. It is the largest pooled analysis of clinician-measured studies, and its nomograms model each measurement as approximately normally distributed. For erect length the mean is 5.17 in with a standard deviation of 0.65 in; for erect girth (circumference) the mean is 4.59 in with a standard deviation of 0.43 in. Veale published these in centimeters, as 13.12 cm and 1.66 cm for length and 11.66 cm and 1.10 cm for girth, and those are the source values everything here is converted from.

Your percentile is simply the share of that distribution sitting at or below your measurement. "About the 62nd percentile" means larger than about 62 of 100 men in the study, and smaller than about 38. One honest caveat before you read too much into a single digit: a clinician-measured study is the ceiling of reliability here, and even careful measurement carries a small margin of error. An eighth of an inch (3 mm) of technique difference can move an erect-length result by roughly five or six percentile points near the middle of the curve. Treat your result as a neighborhood, not an address.

How to measure, and why the method matters

Every number on this page comes from clinician-measured research, so the comparison is only fair if you measure the way the clinicians did. Two conventions matter.

Length is measured along the top, from where the shaft meets the pubic bone to the tip, with the ruler pressed firmly back against the bone. That last part is not a trick to inflate the number. It is the standard because it removes overlying fat, which varies a lot between people and would otherwise make any comparison meaningless. Measure erect, with the shaft held parallel to the floor.

Girth is the circumference at the thickest point, which for most people is mid-shaft. Wrap a soft tape once around, snug but not compressing. No soft tape? Wrap a piece of string around the same spot, mark where the end meets the string, then lay the string flat against a ruler.

Measure twice, on different occasions. Arousal, temperature, and time of day all move these numbers, and a single reading is noisier than most people expect.

The formula

z = (x − μ) / σ    percentile = Φ(z) × 100

x is your measurement in cm, μ is the study mean (13.12 cm for erect length, 11.66 cm for erect girth), σ is the standard deviation (1.66 cm and 1.10 cm respectively), and Φ is the cumulative distribution function of the standard normal curve. Inches convert at 1 in = 2.54 cm before the math runs. We evaluate Φ with the Abramowitz and Stegun error-function approximation (formula 7.1.26), which is accurate to about seven decimal places, comfortably beyond the four decimals this page needs.

Worked example

Say you measure an erect length of 5.5 in and an erect girth of 4.7 in.

Length: 5.5 in = 13.97 cm. z = (13.97 − 13.12) / 1.66 = 0.512. Φ(0.512) = 0.696, so about the 70th percentile: larger than about 70 of 100 men in the study.

Girth: 4.7 in = 11.94 cm. z = (11.94 − 11.66) / 1.10 = 0.254. Φ(0.254) = 0.600, so about the 60th percentile.

What a percentile can and cannot tell you

A percentile locates you in a crowd. It does not grade you. The middle half of men, 25th to 75th percentile, spans only about 4.7 to 5.6 in (12.0 to 14.2 cm) erect, a band you could cover with two fingers. Flaccid size predicts erect size poorly, which is why locker-room comparisons mislead, and partner satisfaction research is a separate question this page does not answer. For the full reference tables, including flaccid measurements and a percentile-by-percentile chart, see our average penis size chart. If you are here for a practical fitting question, the condom size calculator turns girth into a nominal-width recommendation, and the size visualizer shows measurements to scale.

One more thing, said plainly and without judgment: if size worries weigh on you, that is a real and common concern worth raising with a doctor or therapist. Distress about size is far more treatable than most men assume, and bringing it up is routine for the professionals who hear it.

Frequently asked questions

What is the average erect penis size?

The average erect length is 13.12 cm (5.17 in) and the average erect girth is 11.66 cm (4.59 in), based on the largest clinician-measured review to date (Veale and colleagues, BJU International, 2015, up to 15,521 men). Those numbers are smaller than most figures you see online because researchers did the measuring, not the men themselves.

How do I measure erect length correctly?

Measure along the top from the pubic bone to the tip, pressing the ruler gently into the fat pad at the base, while fully erect. That bone-pressed protocol is close to how clinicians measure. Measure two or three times and take the middle value, because a few millimeters of technique difference genuinely moves your percentile.

How do I measure girth?

Wrap a soft tape measure (or a strip of paper you then lay against a ruler) around the thickest part of the erect shaft, snug but not tight. Girth in the Veale data means circumference, the full distance around, not the width across.

Is a percentile of 30 or 40 something to worry about?

No. A 30th or 40th percentile is squarely inside the normal range; in any group of men, someone has to stand at every point of the distribution, and the middle half of men span only about 2.2 cm of erect length. If size worries weigh on you regardless of the numbers, that is a real and common concern worth raising with a doctor or therapist, and doing so is a normal thing to do.

Why is this calculator's average smaller than numbers I have seen online?

Because the data here comes from studies where a researcher measured, using a stated protocol. Self-reported surveys run larger, since men tend to round up and there is no way to verify a number typed into a form. Clinician-measured data is the most reliable available, and even it has a few millimeters of measurement error.

Does this calculator store what I type?

No. Everything runs in your browser and nothing you enter is sent to us or stored anywhere. The share link only exists if you choose to copy it yourself.

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