You order a pair of underwear online, wait for delivery, and when you finally try them on… they’re too tight around the waist or too loose in the legs. Maybe they bunch up when you move, or the fabric cuts into your thighs. Getting the wrong size means wasted money and more discomfort than you started with.
The fix is simpler than you think. Measure your waist and hips correctly, match those numbers to a reliable size chart, and you’ll know exactly which size fits your body. No guessing, no returns, no frustration.
This guide shows you how to measure yourself accurately, how to read men’s underwear size charts in both centimetres and inches, and what factors beyond basic measurements affect your fit. You’ll also learn how different body types and activities change what size works best for you. By the end, you’ll know your exact size and how to buy underwear online with confidence.
What affects your underwear size
Your waist measurement determines your base size, but hip circumference and thigh size also play major roles in how underwear fits. A size that fits perfectly around your waist might feel too tight in the legs if your thighs are larger. The same applies in reverse: underwear that sits comfortably on your hips might sag at the waist if there’s too much extra fabric.
Fabric type and stretch
The material changes how forgiving a size is. Bamboo and cotton blends stretch more than pure cotton, which means they accommodate slight size variations better. If you’re between sizes on an underwear-size-chart-men, stretchy fabrics let you size down without discomfort. Rigid fabrics require exact sizing because they don’t flex with your body when you sit, bend, or move.
Stretch fabric can accommodate up to 5cm variation in measurements, while non-stretch fabric demands precise sizing.
Cut and style differences
Boxer briefs require different sizing than briefs or trunks because they cover more surface area. Longer legs mean you need to account for thigh circumference, not just waist size. Briefs sit higher and focus on waist fit, while trunks fall somewhere in between. A medium in briefs might feel restrictive as a medium in boxer briefs if the leg bands are too tight.
Body shape and proportion
Your build affects which size works best. Men with athletic builds (larger thighs and glutes relative to waist) often need to size up to prevent leg bands from cutting in. Slimmer builds can usually follow standard size charts without adjustment. If you carry weight around your midsection, measure at the widest part of your stomach rather than your natural waistline to get accurate sizing.
Activity level matters too. Active lifestyles demand underwear that moves with you without riding up or chafing, which sometimes means choosing a size with more coverage even if it feels slightly looser when standing still.
Step 1. Measure your waist and hips
Accurate measurements start with the right tools and technique. You need two measurements to match yourself to an underwear-size-chart-men: your waist circumference and your hip circumference. Both numbers matter because underwear fits around your waist and stretches across your hips and thighs. Getting either measurement wrong means ordering the wrong size.
Tools you need
Grab a soft measuring tape, the type used for sewing rather than a rigid metal tape measure. Soft tape wraps around your body without gaps and gives you precise numbers. If you don’t have one, use a piece of string wrapped around your body, then measure the string length against a ruler. You’ll also need a mirror to check the tape sits level, and someone to help if you want the most accurate readings.
How to measure your waist
Stand straight with your arms at your sides and breathe normally. Find your natural waistline, which sits roughly halfway between your lowest rib and the top of your hip bone. This is where your body naturally creases when you bend sideways. Wrap the measuring tape around your waist at this point, keeping it parallel to the floor all the way around.
The tape should sit snug against your skin without compressing it. You should fit one finger between the tape and your body comfortably. Pull the tape too tight and you’ll get a smaller number than your actual size; leave it too loose and you’ll order a size too large.
Measure twice and use the larger number if they differ. Your body shifts slightly between measurements, and sizing up by half a centimetre is better than sizing down.
Read the measurement where the tape meets itself. Record the number in centimetres or inches depending on which underwear-size-chart-men you’ll use. Most Australian brands list both, but international brands might only show one unit.
How to measure your hips
Your hip measurement captures the widest part of your lower body, which includes your glutes and upper thighs. This number determines whether the leg openings will fit comfortably or cut into your skin.
Stand with your feet together and wrap the tape around the fullest part of your buttocks. This typically sits about 20cm below your waistline, but body types vary. Keep the tape level and parallel to the floor, just like you did for your waist. The tape should sit flat without twisting or bunching.
Check the measurement from multiple angles in a mirror to confirm the tape hasn’t ridden up at the back or dropped down at the front. Record this number alongside your waist measurement. If your hips measure more than 15cm larger than your waist, you might need to size up to prevent the leg bands from feeling too tight, even if your waist fits the standard size.
Step 2. Match your measurements to the size chart
You have your waist and hip measurements written down. Now you need to compare those numbers against a standard underwear-size-chart-men to find your size. Most brands follow similar sizing conventions, but the exact centimetre ranges vary slightly between manufacturers. Start with a standard size chart to identify your base size, then check the specific brand’s chart if they provide one.
Standard men’s underwear size chart
This table shows typical size ranges for men’s underwear across Australian and international brands. Your waist measurement determines your primary size, while your hip measurement confirms the fit will work across your thighs and glutes.
| Size | Waist (cm) | Waist (inches) | Hips (cm) | Hips (inches) |
|---|---|---|---|---|
| XS | 66-71 | 26-28 | 81-86 | 32-34 |
| S | 71-76 | 28-30 | 86-91 | 34-36 |
| M | 76-86 | 30-34 | 91-101 | 36-40 |
| L | 86-97 | 34-38 | 101-112 | 40-44 |
| XL | 97-107 | 38-42 | 112-122 | 44-48 |
| 2XL | 107-117 | 42-46 | 122-132 | 48-52 |
| 3XL | 117-127 | 46-50 | 132-142 | 52-56 |
Match your waist measurement to the waist column first. If your waist is 82cm, that puts you in Medium range. Then check your hip measurement against the hips column for the same size. If your hips measure 98cm, they also fall within Medium range, which confirms Medium is your size.
How to read between sizes
Your measurements sometimes land right on the boundary between two sizes. A waist of 86cm sits exactly where Medium ends and Large begins. When this happens, your hip measurement and body type determine which direction to go.
Choose the larger size if your hips measure in the upper half of the size range or if you prefer a relaxed fit. A man with an 86cm waist and 108cm hips should pick Large because his hip measurement sits firmly in Large territory. Sizing down would make the leg openings too tight.
Size up when your measurements fall on the boundary between two sizes, especially if you have athletic thighs or prefer more room to move.
Pick the smaller size if your hips sit in the lower half of the range and you want a closer fit. Someone with an 86cm waist and 94cm hips could wear Medium comfortably because both measurements stay within Medium range. The fit will feel more fitted but not restrictive.
Brand-specific variations
Different brands adjust their size ranges by a few centimetres. SLY Collective’s sizing, for example, might run slightly different from generic department store brands because of their bamboo fabric’s stretch properties and the built-in pouch design. Always check the specific brand’s size chart before ordering, especially when buying from a new company.
Some brands list sizes as numerical (32, 34, 36) instead of letter sizes (S, M, L). These numbers typically represent waist measurements in inches. A size 32 equals roughly 81cm waist, which corresponds to Small in letter sizing. Convert your centimetre measurement to inches by dividing by 2.54, then round to the nearest even number to find your numerical size.
International brands might use different measurement systems entirely. European brands sometimes use numerical sizes that don’t directly convert to Australian letter sizes. When ordering from overseas retailers, look for measurement ranges in centimetres or inches rather than relying on size labels alone.
Step 3. Fine tune fit by body type and activity
Your measurements on an underwear-size-chart-men give you a starting point, but your body proportions and daily activities determine whether that size actually works. Two men with identical waist measurements can need different sizes if one lifts weights four times a week and the other sits at a desk all day. The standard size chart assumes average proportions, but your body might not fit that template. This step helps you adjust your size choice based on your specific build and how you move through your day.
Athletic build adjustments
Men with developed leg muscles from cycling, squats, or sports typically need to size up from what their waist measurement suggests. Your thighs and glutes take up more space than the standard size chart accounts for, which makes the leg openings on your usual size feel restrictive. A 32-inch waist might correspond to Medium in the chart, but if your thighs measure over 60cm in circumference, Large will fit better.
Test this by checking how your current underwear fits around the leg bands specifically. If they dig into your skin or create visible lines through your trousers, go up one size. The waistband might feel slightly looser, but the improved comfort around your legs outweighs that minor trade-off.
Athletic builds benefit most from pouch designs that provide structured support without compression, allowing the larger size to work without excess fabric bunching.
Slim build considerations
Slimmer builds with narrower hips relative to waist size can usually follow the size chart exactly or even size down for a closer fit. Your thighs don’t strain against the leg openings, which means you have more flexibility in sizing. If you measure 76cm around the waist, Medium will work without the leg bands riding up or feeling loose.
Pay attention to waistband tightness instead of leg fit when you have a slim build. The elastic should sit flat against your skin without rolling or gapping. If you find the waistband folds over on itself or you can pull it more than 3cm away from your body, drop down one size.
Activity-based sizing
Your movement patterns throughout the day affect which size prevents chafing and stays comfortable. Desk jobs require less size adjustment because you’re mostly stationary. Physical jobs that involve walking, climbing, or lifting need underwear that won’t bunch or shift, which sometimes means sizing up for better coverage and support.
Active lifestyles specifically benefit from longer leg lengths in boxer briefs, which means choosing a size that prioritizes leg coverage over exact waist fit. If you run, play sport, or walk more than 10,000 steps daily, test your current underwear during activity rather than while standing still. Underwear that feels fine when stationary might ride up or chafe after thirty minutes of movement, which signals you need a different size or style altogether.
Extra tips for buying men’s underwear online
Read customer reviews that mention sizing accuracy before you order. Other buyers tell you whether a brand runs small, large, or true to size, which helps you adjust from the standard underwear-size-chart-men. Look specifically for reviews from people with similar body types to yours, as their experience will match yours more closely than general feedback.
Check the return policy and exchange terms before ordering. Brands that offer free returns or exchanges let you test multiple sizes at home without risk. Order two adjacent sizes if you’re uncertain, try both on, and send back the one that doesn’t fit. This approach costs nothing extra and guarantees you get the right fit on your first purchase.
Free exchanges and returns remove the guessing game from online underwear shopping, letting you test sizes in your own home.
Verify the fabric composition in the product description. Bamboo blends, cotton, and synthetic fabrics all stretch differently, which affects how forgiving the size is. Higher percentages of elastane (typically 5-15%) mean more stretch and flexibility between sizes.
Find your best fit and feel the difference
You now have everything you need to order the right size: your exact measurements, a reliable underwear-size-chart-men to reference, and adjustments for your body type and lifestyle. Accurate sizing eliminates the frustration of returns, the discomfort of ill-fitting underwear, and the uncertainty of online shopping.
Apply these measurement techniques every time you buy from a new brand. Your body changes over time, and different manufacturers use slightly different size ranges, which means checking your measurements again prevents ordering mistakes. Write down your waist and hip measurements and keep them handy for future purchases.
The right size makes all the difference between underwear you tolerate and underwear that genuinely improves your day. Better fit means less chafing, no bunching, and support exactly where you need it. Browse our range of urologist-recommended pouch underwear designed to deliver the comfort your measurements deserve.