How to choose a swim trunks
Updated June 2026Independently researchedNo paid placement.
Focus on three things: length (determines style and mobility), fabric (nylon blends dry fast and hold up to chlorine/salt), and closure (drawstring or button, depending on how secure you need it). The rest, liner vs. no liner, pockets, print vs. solid, is about your comfort and where you plan to wear them.
What length should you choose?
Swim trunks generally fall into one of three camps. Very short cuts, a 3- to 5-inch inseam, give you maximum freedom of movement and a modern, athletic look; they are a favorite among surfers and younger guys. Mid-length trunks around 5 to 7 inches strike a balance that suits most body types and activities, from beach volleyball to casual poolside lounging. Longer board shorts, with an inseam of 7 to 9 inches, offer more coverage and a classic, relaxed silhouette; they’re often preferred by taller men or those who want extra modesty. The key is to pick a length that lets you move comfortably without bunching or riding up. Try on a few different inseams if you can, the right length can make or break how confident you feel on the beach.
What fabric works best for swim trunks?
Most modern swim trunks are made from nylon, polyester, or blends of the two. Nylon is soft, durable, and dries quickly, but it can absorb a bit of water. Polyester is even faster-drying and resists chlorine and fading well, though it can feel slightly rougher against the skin. Many brands now use a blend to combine the strengths of both fibers. Look for a fabric with a bit of stretch (often spandex or elastane added). that extra give makes a big difference when you’re active. Avoid 100% cotton trunks: they soak up water, take forever to dry, and can get heavy and saggy. A good pair should feel lightweight and nearly dry by the time you walk from the water to your towel.
Should you get a built-in mesh liner?
It’s largely a matter of personal preference. A built-in mesh liner provides light support and eliminates the need for underwear underneath; it also keeps everything in place when you’re swimming or surfing. Many guys find it comfortable for active water use. On the other hand, liners can chafe if the trunks are too loose or if you’re sitting for long periods. Some men prefer to wear compression shorts or quick-dry underwear instead. Beach-lounging trunks often skip the liner entirely for a more casual fit. If you dislike liners, look for “linerless” trunks or brands that let you remove the mesh. Either way, just remember: never wear cotton underwear under swim trunks, you’ll end up soggy and uncomfortable.
What kind of closure works best?
Drawstrings are the most common and practical choice. A flat, round, or ribbon-style drawstring lets you adjust the waist easily, and many trunks use a back tie or a hidden drawcord for a cleaner look. A well-secured knot holds up fine in waves, but some swim trunks combine a drawstring with a snap-button for extra security. A simple button-and-fly closure (think casual shorts) can look neater but may loosen over time, especially if the fabric stretches when wet. For surfing or any vigorous activity, a drawstring is the safer bet. If you hate fussing with knots, look for trunks with a flat, no-tie drawstring or a quick-adjust buckle, these are simple and stay put.
How important are pockets and drainage?
Pockets are convenient for carrying keys, a phone, or a wallet when you’re walking around, but they can become water-filled balloons when you swim. Good swim trunks solve this with mesh pockets that drain quickly, or a zippered back pocket that keeps valuables secure. Some designs even have a small key loop inside the main pocket. If you plan to do heavy swimming or surfing, minimize gear: a single zippered pocket or a cinch pocket works best. For poolside or vacation wear, deeper side pockets with small drainage holes are fine, just avoid taking your phone into the water. If a pair of trunks doesn’t drain water properly, you’ll feel weighed down and get a cold, sloshing sensation.
How should swim trunks fit?
The ideal fit is snug enough to stay up when wet but not so tight that they restrict movement or look constricting. Your trunks should sit at your natural waist or just below, and the leg openings should be wide enough to allow a full range of motion, especially if you’re doing anything athletic. A too-loose pair will sag and may lead to embarrassing moments. Try the trunk’s stretch test: if you can squat, lunge, and kick without the waistband rolling or the fabric pulling, the fit is right. Many brands offer a classic straight-leg cut, but some have a more tailored or tapered leg for a modern look. Trust the feel, not just the size on the tag, different brands cut their trunks differently.
Frequently asked questions
Are swim trunks and board shorts the same thing?
Not exactly, though the terms are often used interchangeably. Board shorts are a type of swim trunk, typically longer (long inseam), made of a quick-drying fabric, and designed for surfing, they usually have a lace-up fly and a Velcro or drawstring closure. Swim trunks can be any length and often include a mesh liner. In practice, most versatile swim trunks borrow features from board shorts.
How long should swim trunks be in 2025?
There’s no single trendy length right now, both very short (3-4 inch inseam) and mid-length (5-6 inch) cuts are popular. The best length is the one that flatters your body shape and feels comfortable. If in doubt, a 5-inch inseam is a universally safe bet that works for most guys.
Do I need a drawstring if the waistband is elastic?
Even with an elastic waistband, a drawstring is a smart safety feature. Elastic can stretch out over time or when wet, and the drawstring lets you cinch it securely. Most quality trunks include both for good reason.
Can I wear swim trunks as regular shorts?
You can, but they won’t be as comfortable for all-day wear. Swim trunks lack the structure, pockets, and fabric weight of casual shorts, and the mesh liner (if present) might feel odd in dry, everyday settings. Many brands sell hybrid trunks that double as casual shorts, but that’s a different category.
What’s the best fabric for salt water vs. chlorine?
For chlorine pools, look for trunks made from polyester or a high-polyester blend, chlorine eats nylon over time. For salt water, nylon is perfectly fine, but the sun and salt can fade colors; dark or patterned trunks hide fading better. Both materials benefit from a fresh-water rinse after use.
Should I size up or down if I’m between sizes?
Size down if the trunks have an adjustable drawstring and you prefer a snug fit when dry. Swim trunks loosen up slightly in water (especially nylon blends). If the next size up feels loose in the store, it will likely be too big in the water. A snug fit is safer than a loose one.