Bone pressed vs non-bone pressed: What it actually means

Bone pressed means measuring from the pubic bone on the top side of the shaft. Non bone pressed starts at the skin at the base on the same line. Bone pressed erect length is the standard reference method for comparison with medical studies. In pooled studies, average clinician measured erect penis length is about 13.12 cm, or 5.16 inches, but that figure is not a pure bone pressed average because measurement protocols vary across studies. Photo, hand, or semi erect estimates are far less reliable than a ruler and a soft tape.

Key takeaways

• A 2015 systematic review pooling measurements from up to 15,521 men found an average erect penis length of 13.12 cm, an average stretched flaccid length of 13.24 cm, and an average erect circumference of 11.66 cm.^[1]
• The classic 1996 Journal of Urology paper found that flaccid length is a poor predictor of erect length, which is why “how to measure penis” and “how to measure an erect penis” are not the same question.^[2]
• A 2021 review of studies in which researchers took the measurements placed average erect length at roughly 5.1 to 5.5 inches, shorter than the averages of about 6.2 inches reported in studies that relied on self measurement.^[3]
• Incomplete rigidity can reduce measured erect length, especially in men with erectile dysfunction.
• No validated clinical formula can accurately estimate penis length or girth from a photo, even with hand comparison, because distance, angle, focal length, erection quality, and hand size all change the image.

Why penis measurement is easy to get wrong

Visible length and measured length are not the same thing. Bone pressed erect length is taken with a rigid ruler on the dorsal side, the top of the shaft facing the belly, pressed through the suprapubic fat pad until it meets the pubic bone. Non bone pressed length uses the same top side line but starts at the skin at the base.

The classic 1996 Journal of Urology paper by Wessells and colleagues measured 80 men before and after a pharmacologically induced erection and found that flaccid length did not accurately predict erect length, while stretched length correlated most closely with it.^[2] A casual flaccid measurement, or a photo of a semi erect penis, is therefore not interchangeable with a true erect measurement.

A 2015 BJU International systematic review pooled measurements taken by health professionals in up to 15,521 men and reported an average erect length of 13.12 cm, based on 692 men, and an average erect circumference of 11.66 cm, based on 381 men.^[1] The authors noted that relatively few erect measurements were taken in a clinical setting.^[1] A 2021 Journal of Sex and Marital Therapy review of studies in which researchers did the measuring placed average erect length between 5.1 and 5.5 inches, probably toward the lower end of that range once volunteer bias is taken into account.^[3] Few studies report bone pressed and non bone pressed values in the same men, so the research offers a solid overall average but no accepted separate average for each method.

How to measure length and girth the standard way

To measure erect length, stand upright and place a rigid ruler on the top side from base to tip. Bone pressed length starts at the pubic bone, non bone pressed length starts at the skin at the base, and the difference between them varies from man to man rather than following a fixed published average.

Bone pressed erect length

Bone pressed erect length, often shortened to BPEL, is measured with a rigid ruler placed on the dorsal side from the pubic bone to the tip of the glans. “Bone pressed” means enough pressure to feel bone through the suprapubic fat pad, not a hard shove.

Because the starting point is the bone, bone pressed erect length is the better choice for tracking change over time and for comparing yourself with studies that try to reduce fat pad error.

Non bone pressed length

Non bone pressed erect length uses the same top side ruler position but starts at the skin at the base without compressing the fat pad. Record it separately because it reflects visible length, and do not treat it as interchangeable with bone pressed length after weight change or when the suprapubic fat pad is large.

Most large datasets do not publish both bone pressed and non bone pressed erect values in the same men, so there is no reliable conversion from one method to the other. If you want to measure a flaccid penis, use the same top side line at room temperature and record ordinary flaccid length separately from stretched flaccid length, which means gently extending the shaft to resistance. Stretched flaccid length appears in far more studies than erect length: the 2015 review pooled stretched measurements from 14,160 men but erect measurements from only 692.^[1] In the Wessells study, stretched length was the flaccid measurement that most closely matched erect length.^[2]

Girth and circumference

Penis girth, or circumference, is the distance around the shaft, not the width across it. Measure only when fully erect, wrap a soft tape around the mid shaft, avoid the glans, repeat the reading three times, and average the numbers for a steadier result. In the 2015 review, average erect circumference was 11.66 cm, measured in 381 men.^[1]

Mid shaft means the halfway point between the base and the start of the glans.

Curved penises and photo estimates

If the shaft curves upward or sideways, a flexible tape or a string laid along the top contour can describe surface length along the curve, but a straight dorsal bone pressed ruler measurement remains the standard method for comparison with most published averages. Visual estimates from a photo, even with a hand reference, are not standardized medical methods. The studies behind published averages relied on direct measurement by health professionals.^{[1] [2]}

A hand, a camera angle, and a partially rigid shaft can all distort apparent size, so a photo cannot give you a bone pressed or non bone pressed length.

Conditions that change measured length or visible size

Obesity, erection quality, and Peyronie’s disease can change visible or measured length. Size anxiety can distort perception of size, but it does not change the actual measurement.

Obesity and buried penis. Men with BMI in the obesity range, 30 kg per m2 or higher, often have a larger suprapubic fat pad, which reduces visible shaft and makes non bone pressed erect length look shorter even when underlying corporal length has not changed. This is why the gap between bone pressed and non bone pressed measurements can widen after weight gain. Studies do not standardize body fat, pubic fat pad thickness, erection quality, or where the ruler is placed, so evidence on the average difference between the two methods is mixed and no single average correction fits every man.

Erectile dysfunction. Incomplete rigidity can reduce measured erect length, especially in men with erectile dysfunction. The 2015 review excluded men with erectile dysfunction, so its averages come from men without that condition.^[1]

Peyronie’s disease. Peyronie’s disease can cause curvature, indentation, and loss of length. A 2019 Nature Reviews Urology review notes that mechanical therapies used over long periods can improve curvature and indentation and restore some length, but that recovery to the predisease state is highly unlikely.^[4] A rigid ruler may underread a curved shaft, so follow the contour with a flexible tape or string as well.

Size anxiety. A 2021 counseling review found that self reported penis size runs larger than researcher measured values, and that most men seeking lengthening surgery have normal sized penises.^[3] The question “how does my penis measure up” is often more about perception than anatomy.

Signs your measurement method is off

Most bad self measurements come from the wrong starting point, a partial erection, or trying to compare a ruler measurement with a distorted photo.

• If repeated measurements during the same erection vary noticeably, your ruler position, start point, or erection quality may be inconsistent.
• If you are measuring from the underside, from the scrotum, or from where pubic hair starts, you are adding tissue that scientific studies do not count.
• If you expected a standard 0.5 inch or 1 inch gap between bone pressed and non bone pressed readings, your method may be off. There is no published universal difference that applies to all men.
• If your photo looks much bigger when the camera is close to the tip, you are seeing perspective distortion, not more length.
• If non bone pressed length drops after weight gain but bone pressed length stays similar, the fat pad is the likely reason.
• If you are measuring flaccid length in a cold room, right after exercise, or while anxious, expect more variation than with stretched flaccid or fully erect measurement.
• If an upward curve leaves air gaps between a rigid ruler and the shaft, use string or a flexible tape along the curve.
• If length seems suddenly shorter and you also notice pain, a new bend, weaker erections, or trouble with penetration, book a urology visit.

Myth vs fact

Myth: A hand in the photo lets you estimate size accurately

Fact: No validated medical formula can accurately estimate penis size from photo visual cues or hand comparison, because lens distance, angle, and hand size vary too much. The studies behind published averages used direct measurement by health professionals.^{[1] [2]}

Myth: Scientific studies all use the exact same base to tip method

Fact: Published studies are not perfectly uniform. The 2015 review found the greatest variation between studies in stretched flaccid length and noted that relatively few erect measurements were taken in a clinical setting.^[1] Starting points also differ, some at the pubic bone and some at the pubopenile skin junction, and few papers report matched bone pressed and non bone pressed data, so the pooled 13.12 cm erect average cannot be labeled a pure bone pressed or a pure non bone pressed average.

Myth: Flaccid or semi erect size tells you your true erect length

Fact: Flaccid size is a poor predictor of erect size. In the classic Wessells paper, stretched length tracked erect length far better than ordinary flaccid length, so a quick glance at a flaccid penis is not a valid proxy for a real erect measurement.^[2]

Myth: Bone pressed length is not usable because it “adds hidden inches”

Fact: Bone pressed length is the standard reference method because it reduces error from the suprapubic fat pad and makes repeat measurements more comparable over time. Non bone pressed length is still useful for visible size, but it answers a different question.

What to do if you want a number you can trust

A repeatable measurement taken the same way three times is more useful than any single photo or guess.

1. Step 1: Measure erect length the same way every time. Stand upright. Place a rigid ruler on the top side. For bone pressed erect length, start at the pubic bone. For non bone pressed erect length, start at the skin at the base. Read the number at the tip of the glans, repeat it three times, and average the readings.
2. Step 2: Measure girth and any flaccid number separately. Wrap a soft tape around the mid shaft only when fully erect. If you also want to measure a flaccid penis, do it at room temperature on the top side and record stretched flaccid length separately from ordinary flaccid length.
3. Step 3: Compare only to numbers measured the same way. Do not compare bone pressed erect length to non bone pressed erect length, and do not compare your ruler to a photo, porn frame, mirror angle, or hand reference. If a new curve, pain, or erection loss appears, see a urologist rather than assuming your penis has permanently shrunk.

If worries about size come with weaker erections, low libido, infertility, or fatigue, a medical evaluation can help separate measurement anxiety from a real medical issue.

Veedma offers testing across the U.S. that includes total and free testosterone measured by LC-MS/MS with LH and FSH, or a review of lab results you already have. Licensed providers review the results and, when appropriate, prescribe enclomiphene or the enclomiphene plus tadalafil tablet. Enclomiphene is not an FDA-approved drug; it is prescribed after a provider confirms the diagnosis and is compounded by a licensed U.S. pharmacy.

The bottom line

You cannot accurately estimate penis size from a photo. If you want the standard number, measure a fully erect penis on the top side from the pubic bone to the tip for bone pressed length, record non bone pressed length separately, and measure mid shaft girth with a soft tape.

References

1. Veale D, Miles S, Bramley S, et al. 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 Int. 2015;115:978-86. PMID: 25487360
2. Wessells H, Lue TF, McAninch JW. Penile length in the flaccid and erect states: guidelines for penile augmentation. J Urol. 1996;156:995-7. PMID: 8709382
3. King BM. Average-Size Erect Penis: Fiction, Fact, and the Need for Counseling. J Sex Marital Ther. 2021;47:80-89. PMID: 32666897
4. Tsambarlis P, Levine LA. Nonsurgical management of Peyronie’s disease. Nat Rev Urol. 2019;16:172-186. PMID: 30397330