What Are Swim Shorts? | Casual Coverage For Water & Sun

A pair of swim shorts looks like everyday shorts but is built for the water. They hit just above or at the knee, use quick-drying synthetics like polyester, and usually include mesh liners and drawstring waistbands. Sizing is straightforward: measure your natural waist and the fullest part of your hips, then decide how much leg coverage you want. If you are ready to buy, our women swim shorts roundup cuts through the options to find your fit.

How Swim Shorts Differ From Swim Trunks And Boardshorts

The terms overlap heavily, but the differences come down to length and formality. Swim trunks are a broad category that includes swim shorts, usually with a built-in liner and a shorter, tighter fit. Swim shorts are a sub-style: looser, longer, and more casual. Boardshorts run longer (often below the knee), skip the liner, and use Velcro or lace closures instead of a drawstring. Square-leg swimwear sits between trunks and shorts—tight, mid-thigh, and geared for lap swimming. For the beach or pool, swim shorts give you the most coverage and casual style; for swimming laps, a shorter trunk or square-leg cut creates less drag.

Key Features Of Swim Shorts

Most swim shorts share a short list of design elements that make them water-ready. Knowing them helps you choose the right pair and avoid buying something that will sag or chafe.

• Quick-dry fabric: Almost always polyester, nylon, or a poly-spandex blend. Water beads and runs off, and the shorts dry in an hour or two out of direct sun.
• Built-in mesh liner: Acts like underwear so you don’t need a separate layer. Some shorts omit the liner (common on boardshorts) purposely for a looser feel.
• Elastic waistband and drawstring: Keeps the shorts on in the water without a belt. The string lets you dial in the tightness.
• Side pockets: Usually mesh or drainable mesh. A phone or key will stay dry-ish but probably not fully dry — linings let water flow out when you stand up.
• UPF rating (varies): Some models carry a stated ultraviolet protection factor. When UPF is printed on the tag, it is accurate for the dry fabric; wet fabric blocks less UV. Polyester itself blocks most UV better than cotton even without a rating.

How To Choose The Right Fit

The right fit depends entirely on what you do in the shorts. Lounging at the shore calls for a looser, longer cut with enough room to sit and stand comfortably. Active swimming, bodyboarding, or running into waves needs a closer fit so water drag doesn’t pull them off.

Measure your waist at your natural waistline and your hips at the widest point. Match those numbers to the brand’s size chart—swim sizing varies more than streetwear sizing. Inseam is the other key number: 5-inch inseams hit at mid-thigh and lean sporty; 7-inch inseams land just above the knee and read as classic casual; 9-inch and longer look like boardshorts and suit taller men or anyone wanting maximum coverage. The single most common sizing mistake is buying too baggy—waterlogged fabric drags, and loose shorts feel heavy and cold once you get out.

Common Mistakes To Avoid

The biggest mistake: assuming all shorts are swim-safe. Cotton shorts hold water like a sponge, weigh you down, and never dry. Another common miss is ignoring the liner—if you buy swim shorts without one, you need to wear something underneath. Confusing recreational and performance swimwear leads to buying trunks that are either too baggy for laps or too tight for comfort. And regional naming trips people up: what one brand calls “swim trunks” another calls “swim shorts” or “boardshorts.” Always read the product description for length, liner, and fabric, not just the label.