Men's Underwear Size Guide (Chart Included)

You wouldn’t wear a shirt that’s 2 sizes too big or too small, right? Why? Because you’ll be uncomfortable, of course. Very uncomfortable, in fact. And guess what? The same principle applies to your pants. 

You don’t want to be marching into the fray wearing underwear that is the wrong fit for your body. And no, it’s unfortunately not as simple as just picking a waistband size and calling it a day. 

We all have pretty unique body types and shapes. Some of us have thicker thighs than others. Some of us are taller or shorter. And some have gigantic Jabbas that need an appropriately sized Hutt to call their home. 

Then there’s the question of personal style. It’s a good idea to have this in mind before you read further. Do you favour boxers, briefs, trunks…? The choice is yours and this underwear style guide should help you out. 

So, you’ve chosen your preferred style? Excellent!

Read on and find out how to measure yourself more accurately in order to get that perfect-fitting pair of stylish pants. 

Men's underwear size chart

Underwear Size

Waist (Inches)

















How to measure your underwear size

1. Pick out your preferred style

Hopefully you’ve read our style guide and have your pants of choice in mind. Great!

Your next job is to go and find those bad boys and do some research on them.

Yes. Do your research. If you’re an active type, you’ll want to pay attention to the material of your pants and go for something more breathable. 

2. Measure your waist

Now down to the really important bit. 

You don’t want to measure your waist where you wear your trousers. You want to measure the area of your waist where you wear your pants. This seems obvious, but can trip a lot of people up, so think about it carefully! If you’re wearing pants right now, stand up and pay close attention to where they sit most comfortably on your hips.

Next up, you’ll want to grab yourself a tape measure and get to measuring!

A great method - especially if you have a willing helper for added accuracy and assurance - is to use a piece of string to ensure you get the most accurate measurement. Snip the string where the ends meet and lay it out next to a tape measure on the floor.

Don't forget: UK sizes are measured in INCHES. So make sure you’re not reading the CM side.

Once you have your measurement, take a look at the size chart above and see which category you fall into.

3. Read the packaging/product information

We cannot stress this enough. Read up on your chosen underwear. 

In the present day, there are so many different styles, fabrics, fits, and more, that you’ll want to read the packaging or supporting information to ensure you get the best fit for you. 

Some come with extra pouch space, or extra space for larger thighs. If this sounds like you, check the packaging for info on whether those pants come equipped for your needs. The last thing you want is to stuff your large thighs into tight, uncomfortable pants. 

3. The finger test

This is not as rude as it sounds …. 

When you have your measurement and you’ve diligently read up, it’s time to try on your underwear for size.

One of the issues everybody faces with buying underwear is that you cannot return it if it doesn’t fit …. Would you want to own pants that someone had already tried on? Yuck. Therefore, we recommend taking this step on underwear you already own. You can then read the label on the best fitting pair to use as a guide for your next purchase. 

You don’t want something that’s going to fit too tightly. You want to be able to slip a finger in the waistband comfortably to ensure the best fit. We call this the finger test. 

If you can slip a finger in there comfortably - meaning that the elastic is not squeezing your finger tightly to your body - then, you have a good waist fit.

4. In-between sizes?

If you find yourself on the cusp of the next size up - for example, your waist is 35.5 inches - go for the next size up. You’ll want that extra space. 

There are few things worse than a pair of pants that are much too tight. Just bear in mind that it’s always better to go a little bit larger with pants than a little bit smaller.

Trust us...  

What size underwear do I need?

How about an example? Let’s call our guinea pig, Roger. 

Roger has diligently followed the steps as set out above. He has chosen his preferred style - a mid-length boxer brief.

He has measured his waist with the help of his partner using a piece of string. Laying it out on the floor, Roger discovers that his waist size is 36.25 inches. This slots him quite comfortably into the Large category. 

BUT, Roger has been blessed/cursed with larger thighs. Genetics… what can we say? 

So, Roger takes this into account. He’s purchased pants before that have been too tight on the leg. So, having consulted our guide, Roger proceeds with diligence. 

He does his research. He investigates different brands and styles to find a pair of pants that has been specially crafted for gentlemen with Herculean thighs.

He takes another look at his chosen style - the boxer brief - and reconsiders. With his larger thighs, regular briefs might actually provide him with a more comfortable, chafe-free fit. 

He also has an active lifestyle, so he wants a more breathable material. 

He heads over to our collection of men’s underwear and browses our vast selection of briefs. 

He selects a pair that suits him down to the ground and doesn’t forget to select L for his sizing. 

He waits patiently for his pants to be delivered. 

He wears his new pants with pride and in supreme comfort.  

Be open-minded

This is a key point. You may have a style in mind that you favour above all others. There certainly are pants out there for you in that style, BUT, it can’t hurt to be open-minded about pants if what you’re looking for above all else is a truly comfortable fit. 

After all, 95% of the time, you’re the only person who’ll be seeing your pants. 

Try out different styles and fits to find the one that you prefer. Experiment a little and vary your choices, materials and brands. 

An amazing pair of pants is absolutely worth the investment, so shop around if you want to treat yourself to the very best. 

Refer back to this size guide and keep the chart in mind

If you get stuck trying to figure out your size, don’t forget to return to this guide and follow the simple steps to ensure you find that perfect fit. 

The sizing chart that we have outlined above is representative of the vast majority of underwear brands and styles that we have available across the UK. Don’t forget - you’re looking to measure your waist in inches, not cm! 

When you browse through our Pants and Socks website don’t forget to properly read all of the product descriptions that come up. They’ll provide vital information on the fit and material of the pants that you’re looking at. 

If you have any questions that aren’t answered by the descriptions, then don’t be shy! Get in touch with our team and we’ll be more than happy to help you make that perfect choice. 

So, what are you waiting for?

Grab that string/tape measure, find your size, and treat yourself to a fresh pair of great fitting pants!