Best Running Underwear: Six Pairs Tested for Comfort, Breathability and Value

Introduction

Running-specific underwear has become genuinely popular over the last couple of years, and there are now plenty of brands to choose from, in all shapes and sizes and using very different fabrics. We spent several months running in garments from Ron Hill, T8 Run, SaySky, Crossfly and Run The Wear, covering prices from 15 pounds up to a fairly premium 43 pounds.

The honest headline: every pair tested was comfortable, breathable and trouble-free. What separates them is how each performs in specific conditions, which is how we break down our recommendations at the end.

Why Running-Specific Underwear Matters

The further you run, the more this overlooked piece of kit matters. Fabrics, construction methods and seam placement all play a role in preventing chafing and irritation, and brands have approached these problems in very different ways. All of the options here are men’s fits, but each brand also offers women’s specific fits and sizes.

SaySky Merino Base 180 Briefs

This pair from Danish brand SaySky is constructed from 95 fine Australian merino with 5 elastane, making it very soft against the skin while helping keep you warm in winter and cool in summer. That merino construction makes it highly breathable with strong moisture wicking, and it is odour resistant too. A wide soft elasticated waistband adds comfort, and sizing runs from small to large. At 37 pounds, the merino does push the price up.

Ron Hill Men’s 4.5 Inch Boxer Briefs

Ron Hill is a well-established British running brand, founded by the running legend himself and known for good quality, affordable kit built to last. The men’s 4.5 inch boxer briefs use 88 recycled polyester and 12 elastane in a lightweight, breathable construction with high wicking properties, odour management, and an engineered shaped pouch for support where needed. They come in four sizes from small to extra-large, two colourways, and cost a very reasonable 18 pounds. Notably, Ron Hill was the only brand tested using recycled polyester in the main body of the garment.

T8 Run Commando Running Underwear

Hong Kong based T8 Run makes our favourite all-rounder for warm weather. The Commandos use 90 Italian blend polyamide and 10 elastane, weighing only 40 grams, and T8 claims these are the lightest running underwear in the world. Designed for some of the hottest and most humid climates on the planet, they are extremely breathable with very high wicking properties, a performance waistband, and no inner thigh seam to cut down on chafing. There is even a chafe-free money-back guarantee. Details impress too: the waistband seam is moved off-centre so it does not irritate the centre of your lower back. Five sizes from extra-small to extra-large, at just 15 pounds.

Holding the fabric up to the light, it is practically see-through, which tells you everything about how little material sits against your skin. The result is a pair that feels almost like wearing nothing, while still feeling supported.

Crossfly Pro 7 Inch Boxers

Crossfly was a new name to us. The Pro 7 inch boxers form part of its performance series, so not running-specific, but designed for high comfort and performance during activity. The blend is 85 polyester and 15 spandex, with highly breathable 3D mesh panels placed exactly where breathability matters most. Unique features include Crossfly Cocoon technology for greater support and comfort, and the X-Fly for faster access when nature calls. A wide soft athletic waistband and odour resistance round things off. Five sizes from small to double extra-large, two colourways, priced at 24.99 in the UK.

Run The Wear Men’s Briefs

Possibly the best known running underwear brand in the UK, Run The Wear builds its men’s briefs from 92 polyamide and 8 elastane with a 360-degree seamless design, produced on a seamless machine out of one piece of fabric. That means no side seams and no labels, which significantly reduces the chance of chafing, so much so that the brand offers its own chafe-free running guarantee. The engineered ergonomic fit with four-way stretch lets you run free while still offering good support. Available in blue or black, five sizes, at a competitive 18 pounds.

SaySky Merino Base 180 Boxers

The boxer version of SaySky’s Merino Base 180 uses the same superfine Australian merino wool, so it is very soft against the skin, super breathable, wicks moisture well, and adds an extra level of warmth in cold conditions. The same wide elasticated soft waistband is here, sizing runs small to large, and at 43 pounds this is the most expensive pair we tested.

Best for Hot Conditions

For running in heat, the T8 Run Commandos come out on top. They were specifically designed for hot conditions and it shows the moment you put them on: super lightweight, very breathable, great moisture wicking, and they dry out fast. Thoughtful seam placement avoids irritation and chafing, and the fabric is so light and soft that it genuinely feels like you have nothing on while still feeling supported.

You could run in them all year round, but in really cold conditions, sub-zero territory, they may not add enough warmth, so one of the other pairs would suit that weather better. For hot-weather running, all this performance for only 15 pounds is hard to beat.

Best for Cold Conditions

For proper cold, think Canada or Iceland, freezing sub-zero conditions where keeping warm and protected is critical, the SaySky Merino Base 180 boxers take top spot. Merino wool’s performance properties are well known, but it can often feel itchy against the skin. That was not the case here: the fine Australian merino is plush and soft, and it does not feel like wool at all. It is highly breathable, wicks moisture away well, and has that soft elasticated waistband. At 43 pounds it is a serious investment, but for the coldest conditions where maximum performance is needed, it is probably worth it.

Best Budget Pick

The most affordable award goes to the dependable Ron Hill men’s 4.5 inch boxer briefs. At 18 pounds we did not know what to expect, and were pleasantly surprised by both build quality and performance. Finishing is excellent, the fabrics are good quality, individual mesh panels keep things breathable, seams sit in the right places to reduce chafing, and you get the all-important soft, wide elasticated waistband. The 88 recycled polyester main body is a genuine bonus, and something we would like to see other brands in this test adopt.

Conclusion

Every pair tested here performed well, stayed comfortable, and caused no issues, so it is hard to go wrong with any of them. Pick by conditions and budget: T8 Run Commandos for hot weather, SaySky Merino Base 180 boxers for serious cold, Ron Hill boxer briefs for dependable value, and the rest as strong all-round alternatives. The longer your runs get, the more this small piece of kit earns its place in your wardrobe.