The fabric your underwear is made from affects everything, how you feel at your desk, whether you chafe on a run, and how fresh you stay when the temperature climbs. Yet most blokes grab a pack off the shelf without giving men’s underwear fabric types a second thought. That’s how you end up with a drawer full of pairs that trap heat, hold moisture, or fall apart after a few washes.
Each material brings its own strengths and trade-offs, and the right choice depends on your lifestyle, your climate, and what you actually need from your underwear. At SLY Collective, we landed on bamboo for our boxer briefs after weighing up every option, but we reckon you should understand the full picture before making your own call.
Below, we break down five common underwear fabrics, cotton, polyester, nylon, modal, and bamboo, covering their pros, cons, and best uses so you can choose with confidence rather than guesswork.
1. Bamboo
Bamboo has become one of the more talked-about men’s underwear fabric types in recent years, and for good reason. It sits in a different category to cotton or synthetics, offering a combination of softness, temperature management, and sustainability that most other materials struggle to match.
What bamboo is in underwear labels
When a label says bamboo, it almost always means bamboo viscose or bamboo rayon. Manufacturers break down bamboo stalks into a pulp, then process the fibres into a soft, breathable yarn. The result is a semi-synthetic fabric with natural origins.
Pros for everyday comfort and sensitive skin
Bamboo is genuinely gentle. The fibres are round and smooth, which means no sharp edges poking at your skin throughout the day. If you have sensitive skin or find most underwear irritating, bamboo is worth prioritising.
Cons and common misconceptions
Bamboo is not indestructible, and processing removes some natural properties from the raw plant. It can cost more than cotton, and some brands use the bamboo label loosely, so you need to check the fabric composition before buying.
Not all bamboo underwear is equal. Look for a high bamboo viscose content, ideally above 70%, to get the real benefits.
Breathability, moisture-wicking, and odour control
Bamboo pulls moisture away from your skin and allows air to circulate. It also resists odour better than cotton, which matters during long days or warmer weather.
Temperature regulation and overheating
The fabric adapts to your body temperature rather than trapping heat. This makes bamboo a strong choice for men who overheat easily or work in warm environments.
Durability, pilling, and how to wash it
Bamboo holds up well with proper care. Wash it on a gentle or cold cycle and avoid high-heat drying to prevent pilling and fibre breakdown over time.
Best uses and who bamboo suits best
Bamboo works best for everyday wear, travel, and warmer climates. It suits men who prioritise comfort, run warm, or deal with skin irritation from rougher fabrics.
What to look for when buying bamboo underwear
Check for a bamboo viscose content of 70% or higher. Pair that with a functional design, like a structured pouch for support, and you have underwear that performs across most situations.
2. Cotton
Cotton is the most familiar fabric you’ll find across men’s underwear fabric types, and it’s the default choice for most brands. It’s natural, affordable, and easy to launder, but it has real limitations depending on your lifestyle.
What cotton is in underwear labels
A label showing 100% cotton means a natural plant-based fibre. Many brands blend it with elastane or spandex to add stretch, so check the full composition before buying.
Pros for everyday wear and easy care
Cotton is soft against the skin and needs no special washing routine. It suits men who prefer a straightforward, natural option for low-intensity daily wear.
Cons in heat, humidity, and sweat
Cotton absorbs moisture but holds it against your skin, which increases chafe risk during exercise or hot weather. Once it’s wet, it stays wet.
If you live in a warm climate or sweat heavily, cotton alone will work against you.
Breathability vs absorbency
Cotton breathes well in cool, dry conditions, but its absorbency becomes a liability the moment your activity level rises.
Stretch, support, and shape retention
Pure cotton loses its shape quickly, especially around the waistband. Elastane blends help, but they still stretch out faster than bamboo or synthetic options.
Durability and how long cotton tends to last
Expect one to two years from cotton underwear with regular washing before thinning and distortion set in.
Best uses and who cotton suits best
Cotton works well for sedentary or light activity in cooler climates where sweating is minimal.
What to look for when buying cotton underwear
Prioritise combed or pima cotton for a softer feel, and confirm elastane is included for better shape retention.
3. Modal
Modal sits between cotton and synthetics when comparing men’s underwear fabric types, offering a notably soft feel that many men find more comfortable than either alternative for daily wear.
What modal is and how brands make it
Modal is a semi-synthetic fibre derived from beech tree pulp. Manufacturers dissolve the pulp and spin it into fine, smooth strands that feel softer than standard cotton from the first wear.
Pros for softness and a smooth feel
The fabric’s fine fibre structure gives it an almost silky quality against the skin, making it a solid pick for men who find cotton too rough or scratchy.
Cons for support and long-term wear
Modal loses its shape faster than bamboo or performance fabrics and provides limited structural support on its own. A well-designed underwear construction compensates for this, but the fabric alone won’t hold a firm fit over time.
If support matters to you, the underwear design needs to do the structural work, not just the fabric.
Breathability and moisture management
Modal breathes adequately in mild conditions but doesn’t wick moisture efficiently under real exertion. It handles light warmth reasonably but falls short in high-output situations.
Stretch, drape, and fit through the day
The fabric moves with your body comfortably, though waistbands and leg openings often relax and lose tension after repeated washing.
Durability and washing tips
Wash modal in cold water on a gentle cycle and avoid high-heat drying to reduce pilling and extend its lifespan.
Best uses and who modal suits best
Modal works best for low-activity days and suits men who prioritise softness over moisture control or structured support.
What to look for when buying modal underwear
Seek out MicroModal specifically, a finer and more durable variant, and confirm elastane is included in the blend for better shape retention over time.
4. Merino wool
Merino wool sits at the premium end of men’s underwear fabric types, valued for natural temperature management that most other materials cannot replicate across wildly different conditions.
What merino is and why it feels different to wool
Unlike standard wool, merino comes from Merino sheep and produces fibres fine enough to wear directly against bare skin without the scratching or irritation coarser wool causes.
Pros for odour resistance and all-season comfort
Natural lanolin in the fibre resists odour-causing bacteria, so you can wear merino multiple days in a row without noticeable smell, which makes it particularly useful for extended travel.
Few fabrics match merino for multi-day freshness without washing.
Cons for price and care requirements
Merino costs significantly more than cotton or modal, and most pairs require hand washing or a gentle machine cycle to prevent shrinkage and fibre breakdown over time.
Moisture-wicking and drying speed
The fibre pulls sweat away from your skin effectively, but it dries considerably slower than any synthetic alternative, which limits its appeal during high-intensity activity.
Warmth, cooling, and temperature swings
This fabric regulates body temperature in both cold and warm conditions, making it a practical choice for variable climates or days that shift between environments.
Durability, pilling, and moth risk
Pilling is a real risk under repeated friction, and merino attracts moths in storage, so keep it in sealed containers between seasons to protect the fibres.
Best uses and who merino suits best
Travellers and outdoor enthusiasts get the most from merino, particularly those who need odour control and temperature adaptability across multiple days without access to frequent laundry.
What to look for when buying merino underwear
Look for a micron count below 18.5 for reliable next-to-skin softness, and check that the construction uses flatlock seams to reduce chafe risk during active wear.
5. Synthetic performance blends
Synthetics are men’s underwear fabric types built for output rather than comfort, using polyester, nylon, and elastane as the primary materials across most performance-focused brands.
What counts as synthetic in underwear
Polyester and nylon make up the core of this category. Most brands blend them with elastane to deliver stretch and compression alongside moisture management.
Pros for sweat, sport, and fast drying
Synthetics dry faster than any natural fabric and handle heavy sweat output without saturating quickly, which makes them practical for sport and high-intensity activity.
Cons for heat, smell, and skin sensitivity
These fabrics trap body heat and harbour odour-causing bacteria, making smell a noticeable issue during extended wear, especially in warm conditions.
Synthetics work best as a workout option rather than an all-day choice if you run warm or have reactive skin.
Breathability and airflow in real-world wear
Mesh panels improve ventilation, but synthetic base fabrics still restrict airflow more than bamboo or merino across normal daily conditions.
Support, compression, and chafe risk
The construction delivers strong compression and structure, though tight fits combined with fabric friction increase chafe risk during sustained runs or training sessions.
Durability, elastane fatigue, and washing tips
Wash on a cold cycle and skip the dryer entirely. Heat degrades elastane fibres, which causes waistbands and leg openings to lose tension faster than expected.
Best uses and who synthetics suit best
Synthetics suit gym sessions, trail runs, and high-output sport where fast drying and compression take priority over breathability or extended comfort.
What to look for when buying performance underwear
Prioritise flatlock seams to cut friction risk and confirm that elastane sits around 15% of the blend for lasting stretch without premature fatigue.
What to pick next
Each of the five men’s underwear fabric types covered here has a clear role to play, but most men land in one of two camps. If you run warm, deal with chafing, or spend long days on your feet, bamboo gives you the best combination of breathability, moisture control, and everyday comfort. If your priority is peak athletic output, synthetics handle sweat and fast drying better than anything else.
Your choice also depends on what the underwear is built to do, not just what it’s made from. The best fabric in the world won’t prevent chafe if the cut and construction work against you. A structured pouch design that separates and supports makes a bigger practical difference than fabric selection alone.
Ready to try bamboo with a design that actually works? Check out our men’s bamboo pouch boxer briefs and get your first pair backed by a full comfort guarantee.