Men's Underwear
Men's underwear at FlipBuy UK: 25 multipacks covering cotton-rich boxer shorts, boxer trunks, woven loose-fit boxers, jersey styles and Y-front briefs. Packs of 5 to 12, in sizes small through to 5XL with waist measurements in both inches and centimetres.
Boxers, trunks or briefs
The three cuts do different things, and most men wear one style out of habit rather than because it suits them.
Boxer shorts (woven, loose fit)
The traditional cut: woven cotton, loose through the leg, usually with a button fly. Coolest and most breathable of the three, which is why they suit warm weather and hot sleepers. The trade-off is that loose fabric rides up under trousers and bunches, so they're poor under anything fitted.
Boxer trunks (jersey, fitted)
Shorter leg, stretch jersey, cut close. The most popular style for a reason. No ride-up, no bunching, works under jeans, suit trousers and gym shorts alike. If you're unsure, this is the safe choice.
Briefs and Y-fronts
Least fabric, most support, and completely invisible under fitted trousers. Y-fronts have the traditional front opening. Popular with older wearers and anyone who finds trunk legs ride up on the thigh.
Getting the size right
Underwear sizing is where men most often buy the wrong thing, usually by using their trouser size. Trouser waist sizes run large. A man who buys 34" jeans frequently has a 32" natural waist.
Measure around your natural waist, roughly at the navel, not where your trousers sit, and use the measurement, not the label on your jeans. Every product page here gives waist ranges in inches and centimetres.
If you're between sizes: size up for woven boxers, because they have no stretch and a tight woven waistband is genuinely uncomfortable. Size down for jersey trunks, because the stretch takes up the difference and a loose trunk rides up.
Sizes here run to 5XL on several styles.
Cotton-rich versus pure cotton
Almost everything here is cotton-rich: typically 95% cotton with 5% elastane. That small amount of elastane is what lets a trunk hold its shape through a day and recover after washing. Pure cotton with no stretch bags at the knee and seat within hours.
The trade-off is that elastane degrades with heat. It's the reason underwear loses its shape, and it's almost always caused by tumble drying rather than by wear.
Washing so they last
Wash at 40°C. Turn inside out if the waistband has a printed logo. That's the first thing to crack.
Don't tumble dry on high heat. This is the single biggest cause of underwear failing early. Heat breaks down elastane, the waistband loses its grip, and the fabric goes baggy. Line dry or use the lowest tumble setting.
Skip fabric conditioner. It builds up on cotton and reduces breathability.
When to replace
Underwear is finished when the waistband has lost its stretch, not when it develops a hole. A waistband that no longer sits flat is the sign, once it starts rolling or sliding down, no amount of washing brings it back.
As a rough guide, everyday underwear worn and washed weekly lasts around a year. Buying in multipacks means you can replace the whole batch at once, which is easier than noticing one pair at a time.
Why multipacks
Everything here comes in packs of 5 to 12. The lower cost per pair is the obvious reason; the practical one is that having a full batch of the same age means your underwear drawer doesn't slowly fill with pairs you avoid.
Twelve pairs is roughly a fortnight between washes, which suits most people. Packs of five or six suit topping up a single style you already know fits.
Colours
Most packs here are dark assorted, black, navy, grey, which is the practical choice. Dark underwear hides wear, doesn't show through light trousers the way white can, and doesn't discolour in the wash. White packs are available where you want them under white or very light trousers.
