To measure penis girth, wrap a flexible measuring tape or a piece of string around the thickest part of the erect shaft, typically just below the head. The circumference at that point is your girth measurement. It’s a straightforward process, but a few details affect accuracy.
What You Need
A soft, flexible measuring tape (the kind used for sewing) is the easiest tool. If you don’t have one, a piece of non-stretchy string or a thin strip of paper works just as well. You’ll also need a rigid ruler to measure the string afterward. Avoid using a rigid carpenter’s tape measure, which won’t conform to the curved surface and will give you an inaccurate reading.
Step-by-Step Measurement
Measure while fully erect. A partial erection will give you a smaller number that doesn’t reflect your actual size, and results will vary each time depending on how aroused you are.
Once erect, find the thickest part of the shaft. For most people, this is the mid-shaft area or just below the head. Wrap the measuring tape snugly around that point so it sits flat against the skin without digging in or leaving a gap. Read the number where the tape meets its starting edge. That number, in inches or centimeters, is your girth.
If you’re using string instead, wrap it around the same spot, pinch or mark the point where the end meets the rest of the string, then lay it flat against a ruler to get your measurement.
Where Exactly to Measure
The standard recommendation is to measure at the thickest point of the shaft. Most sources, including clinical references, place this just below the glans (the head). However, some people are thickest at the base or mid-shaft. If your shaft varies noticeably in width along its length, you can take measurements at multiple points. The thickest reading is generally what’s used when people refer to girth.
Factors That Affect Your Results
Don’t be surprised if you get slightly different numbers on different days. Penis size can change noticeably depending on time of day, room temperature, stress level, and how fully aroused you are. Cold temperatures cause temporary constriction, and anxiety can reduce blood flow. For the most consistent result, measure on a few separate occasions when you’re comfortably warm and fully erect, then use the average.
Pulling the tape too tight is the most common mistake. You want it snug against the skin, not compressing the tissue. Think of it like measuring a wrist for a bracelet: firm contact, no squeezing. Likewise, a loose wrap that leaves space between the tape and your skin will overestimate the measurement.
Average Girth for Reference
A large review of over 15,000 men, published by the BJU International, found an average erect circumference of 4.5 inches (about 11.5 cm). The average flaccid circumference was 3.7 inches (9.3 cm). Most men fall within roughly half an inch above or below that erect average. These numbers come from direct measurements taken by clinicians rather than self-reported data, which tends to skew higher.
Tips for a Reliable Reading
- Measure more than once. Take readings on at least three different days and average them. Single measurements are less reliable because of natural day-to-day variation.
- Use the same tool each time. Switching between string and tape, or using different rulers, can introduce small inconsistencies.
- Stand upright. Sitting or lying down can change how blood distributes, potentially affecting your erection and the reading.
- Keep the tape perpendicular to the shaft. Wrapping at an angle adds extra length to the loop, inflating your number.
There is no universally standardized clinical protocol for measuring girth the way there is for length (where pressing to the pubic bone is the accepted method). That said, “thickest part, snug tape, full erection” is the consistent guidance across urology and sexual health sources. Following these steps will give you a number that’s accurate and comparable to published averages.