How to Measure a Penis

Size matters when buying condoms

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A condom that's too small can be uncomfortable, and one that's too loose can fall off. The best way to make sure your condoms fit is to get an accurate measurement of your penis.

Assumptions about penis size from finger length, foot size, and height are not supported by research. The only way to get accurate numbers for fitting a condom is to measure the penis while it's erect.

This article explains the steps to follow to measure the length, girth, and width of your penis. Then, it shows how to use these measurements to choose the right condom size for you.

How to Measure a Penis
Verywell / JR Bee

Measuring Penis Length

Start by measuring the length of your penis:

  1. Position a ruler or measuring tape at the base of your erect penis where it attaches to your body.
  2. Press into your pubic bone as far as you can, until you contact the bone. This is especially important if there's a lot of belly fat. 
  3. Measure from the base of your penis to the end of its tip. 

The average erect penis is a little over 5 inches (13 centimeters) long.

Measuring Penis Girth

Next, measure the girth of the penis—that is, the circumference or thickness.

  1. For this step, use a soft measuring tape or a piece of string. If you choose the latter, make sure it doesn't have any stretch. Using a length of yarn, for example, could result in measurement errors.
  2. Gently wrap the tape or string one time around the thickest part of the shaft of the erect penis.
  3. Note where the ends of the tape meet; that's the number you're looking for. If you're using string, mark where the end of the string meets the rest of it. Then, straighten out the string and use a ruler to measure the distance from the mark to the end. 

The average penis is around 4.5 inches (11.5 centimeters) in girth.

Measuring Penis Width

Some condoms are sized according to width or diameter. You can find this measurement the same way you would find the diameter of a circle. First find the girth using the method described above. Then, simply divide that number by 3.14.

Penis size can vary due to stress, fatigue, frequency of sexual activity, and level of arousal. So you may want to do several measurements at different times throughout the day, over several days.

Using Your Penis Size to Choose a Condom

Once you are confident that you have figured out your penis size, you should be able to determine what size condom you need.

If your penis is of average size, a standard-size condom should provide you with an accurate fit. A larger-than-average penis may need a condom labeled "large," whereas a penis that is smaller may need a condom labeled "snug."

Remember, when it comes to condoms, size matters: The better the fit, the better it will protect you against unwanted pregnancies and sexually transmitted infections.

Summary

To determine the size of your penis, you will need to measure its length, width, and girth. Some people use a ruler or measuring tape, others use a string. Just make sure that whatever you use does not stretch, as this can cause inaccuracies in the measurement. Once you have established the size of your penis, you can use this information to find a condom that fits you properly.

A Word From Verywell

A condom's purpose is to protect you and your partner from sexually transmitted infections and unwanted pregnancies, but it can't do that if it breaks or falls off. Don't just assume that whatever condom you pick will work just fine. Given the risks involved with unprotected sex, it's worth it to measure your penis accurately. That way, you can choose a condom that protects you and feels comfortable.

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3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Prause N, Park J, Leung S, Miller G. Women's preferences for penis size: A new research method using selection among 3D models. PLoS ONE. 2015 Sep;10(9):e0133079. doi:10.1371/journal.pone.0133079

  2. Veale D, Miles S, Bramley S, Muir G, Hodsoll J. 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 Dec;115(6):978-86. doi:10.1111/bju.13010

  3. Veale D, Miles S, Bramley S, Muir G, Hodsoll J. 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 Dec;115(6):978-86. doi:10.1111/bju.13010