To get an accurate measurement, you need a full erection, a rigid ruler or flexible tape measure, and a consistent technique called the “bone-pressed” method. This is the same approach used in clinical studies, so it gives you a result you can compare to published averages. The whole process takes about a minute.
How to Measure Length
Place a rigid ruler or straight measuring tape along the top of your erect penis, starting where the shaft meets your body at the pubic bone. Press the end of the ruler firmly into the pubic bone, pushing past any fat pad or pubic hair. Then measure in a straight line from that point to the very tip of the head. This “bone-pressed erect length” (sometimes abbreviated BPEL) is the standard used in virtually all medical research, which means it’s the only measurement that gives you a meaningful comparison to published statistics.
Pressing into the pubic bone matters because the fat pad above the base of the penis can hide a significant portion of the shaft, especially as body weight increases. Without that press, two people with the same actual penile length could get very different numbers depending on their body composition. Measuring along the top, rather than the underside, also keeps the measurement consistent regardless of any natural curvature.
How to Measure Girth
Use a flexible, non-stretchable tape measure. While fully erect, wrap the tape around the shaft at the midpoint of your total length. If your length is 5 inches, that midpoint is 2.5 inches from the base. The number where the tape meets itself is your circumference, or girth.
If you don’t have a fabric tape measure, wrap a strip of paper or a piece of string around the shaft at the midpoint, mark where it overlaps, then lay it flat against a ruler. Avoid using anything elastic, which will stretch and give you a smaller number.
Why Erect Measurements Are the Standard
Flaccid size is a poor predictor of erect size. A study published in The Journal of Urology found that neither age nor flaccid length accurately predicted how long the penis would be when erect. In that study, the mean flaccid length was 8.8 cm (about 3.5 inches), while the mean erect length was 12.8 cm (about 5 inches). Some men who measured shorter while flaccid ended up well above average when erect, and vice versa.
If you can’t get a full erection for measurement, the next best option is stretched flaccid length. Gently stretch the flaccid penis to its maximum length while holding the ruler against the pubic bone. Research confirms that stretched length correlates closely with erect length, which is why urologists often use this method in clinical settings. In the same study, stretched length averaged 12.4 cm, only about 4 millimeters shorter than the erect average.
How Your Numbers Compare to Averages
A large meta-analysis in the World Journal of Men’s Health pooled data from 75 studies and over 55,000 men. The averages were:
- Erect length: 13.93 cm, or roughly 5.5 inches
- Erect girth: approximately 4.5 inches (11.5 cm), based on data from the Sexual Medicine Society of North America
- Flaccid length: 8.70 cm, or about 3.4 inches
Most men fall within about an inch above or below these averages. The clinical threshold for a micropenis in adults is a stretched length below 7.5 cm (about 3 inches), which is defined as 2.5 standard deviations below the mean. This is a formal medical diagnosis and is quite rare.
Using Your Measurements for Condom Fit
Your girth measurement is actually more important than length when choosing condoms, because a poor circumference fit is what causes slipping or discomfort. To match your girth to a condom’s listed width (sometimes called “nominal width” or “flat width”), divide your circumference by 3.14. That gives you your diameter, which you can compare directly to the width printed on the box.
As a rough guide: if your girth is around 4 to 4.5 inches, standard-fit condoms with widths around 2.0 to 2.09 inches will typically work. If your girth is under 4 inches, look for snug-fit options with widths closer to 1.9 inches. If your girth is over 5 inches, larger-fit condoms with widths of 2.13 to 2.24 inches will be more comfortable and less likely to break.
Tips for a Consistent Measurement
Erection quality varies day to day based on arousal, stress, temperature, and blood flow. For the most reliable number, measure on a few different occasions and average the results. Make sure you’re at full erection each time, since even a slightly incomplete erection can shave off a quarter inch or more.
Always measure from the top of the shaft, not the side or underside. If your penis curves noticeably, use a flexible tape measure and follow the curve along the top surface rather than trying to measure a straight line through the air. Keep the same pressure against the pubic bone each time. These small consistencies are what separate a reliable measurement from one that fluctuates by half an inch every time you check.