How to Measure Your Penis Size

Know your numbers to choose the right condom size

Man holding ruler
Photo © Dawn Stacey

There is a very good reason to measure your penis size. When it comes to choosing the perfect condom, size can make all the difference. Many men complain about condoms fitting too tightly, and one that is too loose can come off prematurely. One way to be sure you're getting the best fit is to measure your penis.

To accurately measure your penis size for a condom, you must have an erect penis. Studies have proven that measuring your limp penis won't give you accurate numbers for your length and girth when erect.

How to Measure Your Penis Length

Start by measuring the length of your penis:

  • Use a ruler or measuring tape.
  • Position it at the base of your erect penis, where it attaches to your body.
  • Make sure to press into the pubic bone as far as you can because fat can hide the length of your penis. This is especially important if you have belly fat. Be sure to press in until you are contacting the bone.
  • Measure your penis length by marking how long it is from the base, all the way to the end of the tip. 

Measuring Your Penis Girth

Next, you'll measure the girth of your penis (that is, the circumference or thickness):

  • For this step, use a piece of string (or something similar) or a soft measuring tape. Just don't choose something like yarn that might stretch, as that could introduce measurement errors.
  • Gently wrap the string one time around the thickest part of the shaft/body of your erect penis.
  • Mark where the string meets.
  • Then measure the distance of the string distance with a ruler. You could also do the same thing with the soft measuring tape, and just mark the measurement once you reach around the penis.

Measuring Your Penis Width

You may also want to know the width or diameter of your penis—since some condoms provide this measurement:

  • You can determine your penis width or diameter by taking the girth measurement you got and dividing it by 3.14. You'll probably want to use a calculator or calculator app to be sure you get the right answer.
  • The resulting number is the width of your penis.

Double Check Your Penis Size

You want to get the most accurate measurement of your penis size. To do this, you should repeat the above steps at different times throughout the day, over several days. Penis size can vary due to stress, fatigue, the frequency of sexual activity, and arousal levels.

What's the Average Penis Size?

Now that you have a good idea of your penis size, you can compare it with the average penis size.

  • The average erect penis length is 5.5 to 6.3 inches (139.7 to 160.0 mm or 14.0 cm to 16.0 cm).
  • The average penis girth ranges between 4.5 to 5.1 inches (114.3 to 129.5 mm or 11.4 cm to 13.0 cm).
  • The average width is about 1.4 to 1.6 inches (35.6 to 40.6 mm or 3.6 mc to 4.1 cm).

If your penis size is close to these averages, then a standard size condom should provide you with the most accurate fit. If your measurements are larger or smaller, you can use them to choose the right size of the condom.

While there are some popular reports of average penis size by country or culture, this review couldn't draw any conclusions from the research studies.

If you are going to be shopping for condoms in other countries, know your measurements in centimeters and millimeters be sure to check the label as manufacturers might label sizes differently.

Will Your Penis Size Change With Age?

Your penis grows in size from the onset of puberty until you are fully mature. The average penis size doubles from age 10 to 18. Depending on the age at which puberty starts for any young man, some size increase might continue until age 20.

At full adulthood, a review of studies found no significant correlation between advancing age and penile size. Overall, there was only a centimeter of difference in the average penis size for men between the ages of 20 and 70.

These studies didn't measure the same men at different ages. There can be changes in erection size and the onset of erectile dysfunction as a man ages, as well as developing curvature. Also, gaining weight at any age can develop the fat pad at the base of the penis, hiding some of its length. These may affect a man's choice of condom sizes.

Meanwhile, other assumptions about penis size from finger length, foot size, and height weren't strongly supported by research. Measuring is still the way to go for accuracy.

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. Use this condom size chart to compare the sizes of the most popular condom types and find the one that will be a good fit for you.

A Word From Verywell

It's normal to want to know how your body compares with the average. In this case, that interest has a practical use. It is important to use the correct condom size so it won't break or slip off. If you know your numbers, you'll be able to shop for the right size with confidence. If you notice any unusual changes in your penis or erection, discuss them with your doctor.


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Herbenick D, Reece M, Schick V, Sanders SA. Erect Penile Length and Circumference Dimensions of 1,661 Sexually Active Men in the United States. The Journal of Sexual Medicine. 2014;11(1):93-101. doi:10.1111/jsm.12244. 

Neinstein, LS. Adolescent Health Care: A Practical Guide. 2016.

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 International. 2015;115(6):978-986. doi:10.1111/bju.13010.