Men's measuring guide for underwear

A Guide to Men's Underwear Sizes

Wearing underwear that fits you perfectly

Your underwear size is important. It's your most private garment, the first on and the last off. It ought to fit you like a second skin.

Crossfly Ikon X - Men's underwear as a second skin

But for some, finding the right size in your perfect underwear isn't always easy; understanding body measurements and reading a size chart can easily lead one astray.

This is because everyone's body has a unique shape and proportion. One isolated measurement can mislead your size choice and you may find that your size in one style, boxers or briefs, may not be consistent for the others. This is because of the differences in proportion between these styles, the fabric they use or the particular brands that manufacture them. 

In this blog, we'll cover the important measurements for determining your correct size, and how to use a size chart to make the right choice every time.

Grab a measuring tape!

How do you determine underwear size?

Firstly, you must get the correct waist measure: the most important single measurement for choosing underwear size.

Wrap your measuring tape around your waist at the position you place your underwear's waistband. Stand naturally, and don't wrap it too tightly: leave a finger's width in between the tape and your skin.

How to measure for your underwear

If your tape measure is too rigid for this, use a string, shoelace, or even charging cable to wrap around your waist; then grab where the full loop connects and take that length to the tape measure!

Other body measurements

Your waist measurement is most important, but should you consider other body measurements in your decision? Perhaps you're a weightlifter with large leg muscles. It may be that a pair of briefs fit your waist but constrict your thighs.

Weightlifting legs

It could also be that a pair purchased for wider hips (or more bodacious buttocks) will have far too much fabric for your legs, leaving you swimming in an excess pool of cotton. Changing styles or choosing a smaller size may correct the problem.

So while the size of your shoulders and chest won't affect your underwear size, differences in torso proportion could be cause for adjustment.

If this is the case for you, you could consider switching from boxers to briefs (or vice versa). Take stock of how your favorite underwear fit. Do you wish they had more fabric for your legs or is the excess causing bunching in your jeans? It's a question that must be answered individually.

Trying out men's underwear

If you want to order some underwear but aren't sure which size to get, look for a site with a sale or bundle offers! This will make your experiment less burdensome on the wallet.

What is the average underwear size for men?

The answer to this question depends on what you consider an average size.

Let's take a common pants size: 34/36. This first number is the waist measurement, although you'll find most pants don't use the literal measurement, but one that is slightly offset. A "34" waist may correspond to a literal measurement of 32 inches. So don't just use your pant's size tag!

The average American man's waistline is closer to 40 inches, so this number is highly variable, and you may be opting for a larger size.

Crossfly Sizing detail

What size is 34 in men's underwear?

For most brands, a size 34 will be a medium underwear size. If you're leaning toward one brand, look for their size chart on the website, as these measurements aren't always consistent.

Corresponding men's underwear sizes

While most underwear will come in a huge range of sizes, here's Crossfly's straightforward, no-nonsense sizing:

  • 29"-31": S
  • 32"-34": M
  • 35"-38": L
  • 39"-42": XL
  • 43"-45": 2XL

Some brands make underwear up to 6XL!

But as we aforementioned, materials used in the underwear will affect the fit. This is the case with Crossfly’s IKON and IKON X styles which are made from modal, a super soft, super comfortable and very stretchy fabric. This stretchiness means that these styles fit slightly larger so if you’re on the cusp of a Medium/Large, opt for a Medium. On the other hand, the Pro 7” Boxers are true to size.


Many variables determine the best size of underwear for your body. You'll find that different brands and different regions will present the sizes differently. Your French size may not be your American size or your English size.

Crossfly's underwear is designed to fit a wide variety of people, with a thoughtful design that supports your body without constricting it. Check out our styles to find a pair that's perfect for you!

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