Men's Underwear: Fit, Fabric and When to Replace It
Men's underwear gets replaced when it fails rather than when it should, which is why most drawers contain a working half and an archive. The decision itself is simple: pick the cut that suits the trousers you wear, buy cotton with a little elastane in it, and go by the chest and waist measurement rather than the letter on the packet. Everything else is preference.
At a glance
- Trunks under close trousers, boxer shorts under loose ones, briefs if you always have.
- Around 95 per cent cotton with 5 per cent elastane is the useful blend. All cotton bags at the knee.
- Continental brands size on the waist measurement, and it runs smaller than UK labelling.
- A slack waistband is the end. No amount of hot washing brings it back.
- Multipacks are cheaper by the pair and make replacing the whole set easy.
- Trunks, boxers and briefs
- What the fabric is doing
- Sizing, and why yours may be wrong
- When to replace a pair
- Washing so they last
Trunks, boxers and briefs
The cut follows the trouser. A trunk has a short leg that sits mid thigh and stays put, which is what you want under a slim or tapered trouser where anything looser will show a line. A boxer short is roomier and sits longer, better under a relaxed cut or a suit trouser with some width. A brief has no leg at all and is the right answer for anyone who has always worn them and sees no reason to stop.
- Trunk: mid thigh leg, close fit, no ride up under close trousers
- Boxer short: longer leg, more room, better under a fuller cut
- Brief: no leg, most support, least bulk under anything
What the fabric is doing
Cotton is comfortable and breathes, and on its own it stretches out during the day and stays stretched. That is the bagging at the knee that makes a pair feel finished by three in the afternoon. A small amount of elastane, usually about five per cent, gives the fabric recovery, so it returns to shape each time instead of gradually giving up.
Anything fully synthetic dries faster and is worth having for the gym, though it will not feel the same in an office chair for eight hours. For everyday wear, cotton with a little stretch is the blend that solves the most problems at once.
Sizing, and why yours may be wrong
European brands size on an actual waist measurement, and British sizing has drifted upwards for years, so plenty of men are wearing a size that was correct on the label and never on them. If the waistband rolls, it is too small. If it sits without gripping and you never think about it, it is right.
Buy one pack, wear it a week, then buy the rest. It is a cheap experiment and it settles the question for years, since the same brand in the same size behaves consistently. Our underwear is mostly Bugatti and HJ, both of which size honestly.
When to replace a pair
The waistband tells you. When the elastic no longer holds without folding over, the pair is done, whatever the fabric looks like. Thinning at the seat is the second sign and usually arrives later. Neither is fixable, and both are usually ignored for about a year longer than they should be.
Replacing the whole drawer at once is easier than replacing pairs as they fail, because a set bought together wears out together and you are never left picking through. Multipacks make that straightforward and cost less per pair.
Washing so they last
Forty degrees, and no hotter. Heat is what kills elastane, and once the stretch has gone the fit never comes back. Tumble drying does the same thing faster, so line dry where you can and take them out of a dryer while still slightly damp if you cannot.
Skip the fabric conditioner here too. It coats cotton and reduces breathability, which is the one property you are paying for. Have a look at the socks while you are at it, since they fail on the same timetable and nobody ever notices until a Monday morning.
Frequently asked questions
What is the difference between trunks and boxer shorts?
Length of leg and how close the fit is. A trunk has a short leg that sits around mid thigh and stays where it is put, which makes it the right choice under a slim or tapered trouser where a looser cut would show through. A boxer short has a longer leg and more room, which suits a fuller trouser or a suit cut with some width. Neither is better in general terms, but one of them is better under the trousers you actually own.
Should men's underwear be pure cotton?
Usually not quite. Pure cotton breathes well but stretches through the day and does not recover, which is the bagging that makes a pair feel worn out by mid afternoon. Around five per cent elastane gives the fabric its shape back each time, and the cotton still does the breathing. Fully synthetic fabrics dry faster and suit the gym, though they are less comfortable for a long day sitting down. Cotton with a little stretch handles most situations.
How do I know if I am wearing the wrong size?
Two signs. If the waistband rolls or folds over on itself, it is too small. If it slides down or you find yourself adjusting it, it is too big. Correctly sized underwear is something you stop noticing. European brands size on a real waist measurement and British sizing has drifted larger over the years, so quite a few men are wearing a size that matched the label but never matched them. Buy one pack, wear it for a week, then buy the rest.
When should underwear be replaced?
When the waistband stops holding without folding over, which is the elastic giving up rather than the fabric wearing out. Thinning at the seat is the second sign and usually arrives later. Neither can be repaired and both tend to be tolerated for far longer than they should be. Replacing the whole set at once is easier than replacing pairs one at a time, because underwear bought together wears out together rather than leaving you sorting through a mixed drawer.
What temperature should I wash underwear at?
Forty degrees is right, and hotter is what shortens its life. Heat degrades elastane, and once the recovery has gone from the fabric the fit never returns. Tumble drying does the same damage more quickly, so line dry if you can, or take them out of the dryer while still slightly damp. Leave the fabric conditioner out as well: it coats the cotton and reduces breathability, which is the property you bought the cotton for in the first place.
