Measured: Judged by ease: the inches of extra cloth beyond the body measurement at chest, waist and hip.
The basics
What to know about men's swim trunks
Built to be soaked repeatedly
Swimwear is clothing built to be soaked over and over, and every feature on the rack follows from that demand. Shells are polyester or nylon because neither fiber holds much water, waistbands rely on elastic or a flat tie because wet cloth grows heavy and drags, and good pockets carry drain holes because a trapped cup of water tugs the suit down with every step out of the pool. Length gets quoted by inseam, the measurement along the inner leg from the crotch seam to the hem. The range runs from a swim brief with no leg at all to a board short ending at the knee.
What sits inside it
Two build questions sort every suit before style enters the picture: what sits inside it, and how it closes. A liner, the mesh or soft knit brief sewn into the waistband, means the suit works with nothing underneath. Makers leave it out of most longer styles without advertising the fact. This is the most common unpleasant surprise in this aisle. Closure behaves differently once wet, since elastic plus a drawcord keeps gripping as the fabric gains weight, while a lace-up flat front trades that security for a waistband that never digs in when you lie down. Fiber then picks your water. Nylon feels softer against skin and breaks down within months of regular chlorine, while polyester shrugs pool chemicals off for seasons. Pool regulars buy polyester and ocean swimmers can choose on feel.
Time in the water sorts it
Time in the water is the sorting question, and the six guides below map onto it. An hour of swimming and lounging at a pool or beach is swim trunks territory. Lap counts and training sessions point to swim briefs or jammers, the two fitted racing shapes, and the choice between them rests on how much leg you want covered rather than on speed. Surfing and long sessions belong to board shorts, cut past mid thigh with a flat front so nothing rubs against a board. A day that drifts from the water to a lunch table with no change of clothes is exactly what hybrid shorts exist for. Strong sun over any of these adds a rash guard on top, because fabric keeps blocking ultraviolet long after sunscreen has washed off.
Swimming well against looking good
The standing trade is that performance and disguise pull opposite ways. The suits that swim best, briefs and jammers, look most like equipment on land. By comparison, the pair that passes at lunch, the hybrid, arrives unlined and presses its stiffer waistband into you on a turn. Trunks hold the middle ground and satisfy most swimmers most of the time. Quick drying is the one requirement with no exceptions, since fabric that stays damp through an afternoon delivers the chafing and the chill that end beach days early. That is the whole case against swimming in anything cotton.
Turn it inside out
A few dry checks predict how a suit behaves wet. Turn it fully inside out, settling the liner question and tracing any leg elastic with a finger to find rough edges before your skin does. Pull the waistband wide and watch it recover, because elastic that returns slowly when new collapses completely once chlorine has worked on it. Probe the bottom of every pocket for a metal grommet or a mesh panel, and hold any pale pair toward the light, since a weave you can see through dry turns transparent in the water. On a rash guard, a printed UPF number on the label outranks any general sentence about sun protection.
Chlorine keeps working after you leave
Chlorine and sun keep working on a suit after you leave the water, so care is mostly about the first ten minutes. Rinse in cool fresh water the same day, pool or ocean, because dried salt stiffens the weave and residual chlorine keeps eating the stretch fibers. Press the water out into a towel rather than wringing, as twisting snaps elastane along the fold lines. Shade beats sun for drying, given that ultraviolet light fades dye and cooks elastic. Hot tubs deserve a cheap dedicated suit of their own, since hot chlorinated water does more damage in an evening than a pool does in a month.
Buyer checklist
Before you buy men's swim trunks
Fit names are only a starting point. Measurements, cloth and construction tell you how a garment will actually wear.
01
Measure the key points
Use chest, neck, sleeve, waist and inseam measurements where relevant, and compare them with the item chart.
02
Fit the hard-to-alter areas first
Shoulders, collar and rise should sit correctly before you consider easier alterations such as hems and sleeve length.
03
Check fiber and fabric weight
The same style can feel very different in lightweight cotton, dense denim, wool or a high-stretch blend.
04
Plan for care
Check washing, pressing and dry-cleaning needs before deciding whether the garment suits everyday use.
Try the suit with the drawcord untied; elastic that grips on its own dry keeps gripping when water doubles the fabric weight.
A trunk hem belongs 2 to 4 inches above the kneecap standing; any longer and it swims like a board short whether or not it is one.
Bring one knee to your chest in the fitting room; a tie front that digs into your stomach there digs on every pool ladder.
Check inside for a liner before you pay, then trace its leg openings with a finger, since scratchy elastic there ends a beach day early.
Order jammers and briefs in your measured waist even when the first wear feels tight; compression knits loosen with use. A comfortable fit new means a failed fit within months.
Care
Caring for men's swim trunks
Rinse in cool fresh water the same day you swim, since chlorine left in the fiber keeps breaking down the elastic overnight.
Never machine dry swimwear; the hot drum finishes off whatever stretch the chlorine has already weakened.
Run a detergent wash only every few wears, cold and softener free, because softener coats the fiber and slows the drying you bought the suit for.
Rotate two suits if you swim most days, as elastic that never dries fully never springs back fully.
Store everything bone dry, since a damp suit folded into a bag mildews within days and synthetic fabric never completely releases the smell.
Questions
Common questions
Do you wear underwear under swim trunks?
No. The liner does the job of underwear, providing hold, coverage and quick drying in one layer. Cotton boxers underneath soak up water, stay wet for hours, show through light fabric and chafe at every seam. If the pair has no liner, wear a synthetic swim brief or a fitted synthetic boxer under it, never anything cotton.
Why did my trunks go baggy and see-through after one summer?
Chlorine, almost certainly. Nylon and elastane both break down in pool chemicals, so a suit swum weekly loses its snap and its opacity within months. Ocean water is gentler as long as you rinse the salt out. Frequent pool swimmers should buy polyester, which resists chlorine for seasons instead of weeks. Rinse the suit in fresh water the day it gets wet.
Can I swim in regular gym shorts?
Physically yes, and many pools will stop you at the door. Gym shorts lack drainage, their liners are cut for running rather than water, and loose knits shed fibers that clog pool filters, which is why lifeguards object. At a lake or beach nobody minds, but the shorts hold water and dry slowly. A cheap pair of true trunks beats the compromise.
Is it fine to cut the mesh liner out of trunks?
Yes, with small scissors kept close to the waistband seam, and plenty of people do it. The trunks then behave like board shorts, so plan on wearing something underneath. Nothing structural depends on the liner as long as you avoid nicking the shell or the waistband stitching. Try a knit-lined pair first, though, since soft liners solve most mesh complaints.
Why do my shorts fill with air when I get in the water?
Air trapped in the legs has no exit, so it bubbles the fabric up until pressure pushes it out past the waistband. Loose cuts with tightly woven shells trap the most. The balloon is harmless and passes in seconds, and pressing the fabric down releases it faster. Suits with drain grommets vent sooner, while fitted styles such as jammers never do it at all.
What should I wear to a pool that bans loose shorts?
Fitted swimwear, meaning jammers or swim briefs. The rule is standard across much of continental Europe and at many competitive pools, on hygiene grounds. A fitted suit is rarely worn as street clothing. That is why it carries less dirt into the water. Jammers are the easy answer if a brief feels exposed, covering hip to knee while satisfying every fitted-suit requirement.
Does a rash guard replace sunscreen?
Only where the fabric covers. A UPF 50 top filters all but about 2 percent of the ultraviolet reaching the cloth, and that protection never rubs off or washes away, which beats any lotion for the torso. Your neck, face, ears, hands and legs stay exposed, so sunscreen still belongs there. In the water, fabric holds its rating while sunscreen thins by the hour.
