Swim Trunks vs Board Shorts: Key Differences
By tomboyx | Premium Underwear for All Day Comfort. Fit for You. | Published: 2026-10-17
Category: Comparisons
Not sure whether to choose swim trunks or board shorts? We break down the key differences in length, features, and versatility so you can pick the right pair for your summer plans.
Quick answer
Swim trunks and board shorts differ mainly in length, features, and intended use. Swim trunks (4.5–5 inches) offer a shorter, sportier cut that dries fast and works well for active swimming. Board shorts (7 inches or longer) provide more coverage, a relaxed fit, and often include pockets and a lace-up fly for casual beach or land wear. Your choice depends on how you plan to use them and the look you prefer.
Length and coverage
The most obvious difference is inseam length. Swim trunks typically fall between 4.5 and 5 inches, giving a more modern, athletic look that shows more leg. Board shorts usually have a 7-inch or longer inseam, offering more coverage and a classic surfer aesthetic. Shorter inseams can feel more freeing in the water, while longer ones provide extra sun protection and a more modest silhouette.
If you're between sizes or unsure about length, consider what activities you'll do most. For swimming laps or playing in waves, shorter trunks reduce drag. For lounging on the sand or walking around town, longer board shorts feel more like everyday shorts.
Features and construction
Swim trunks often have a built-in mesh liner, elastic waistband with a drawstring, and minimal hardware. They're designed for quick drying and easy movement. Board shorts typically skip the liner (wear them with underwear or a swim brief) and may have a lace-up fly, side pockets, and a longer, relaxed fit. Some board shorts are unlined with a fully elastic waistband for easy on/off.
Reversible options give you two looks in one – a great space-saver for travel. For example, the Swim 5" Reversible Board Short offers a shorter inseam with two colorways, while the Swim 4.5" Reversible Short provides the same versatility in a classic trunk length. Both feature UPF 50 protection and chlorine/saltwater resistance.
Material and durability
Most modern swimwear uses recycled polyester blends that resist chlorine, saltwater, and fading. Look for flatlock seams to prevent chafing and anti-cling, anti-static properties. Higher-quality options will hold up better over multiple seasons. Both swim trunks and board shorts can offer UPF 50 sun protection – a key feature if you spend long days outdoors.
Sustainability matters too: some brands recycle plastic bottles into their fabrics. For instance, each 7" Pull-On Board Short uses the equivalent of 7 recycled water bottles. That's a small but meaningful choice if you're eco-conscious.
Swim trunks vs board shorts: tradeoffs
- Length: Shorter trunks (4.5–5 in) show more leg and reduce drag in water. Longer board shorts (7 in) offer more coverage and sun protection, but can feel heavier when wet. Choose shorter for swimming, longer for lounging.
- Features: Swim trunks often have a built-in liner and minimal pockets. Board shorts may have pockets and a lace-up fly, but typically require separate underwear or a swim brief. Decide if you want all-in-one convenience or the ability to customize your under-layer.
- Versatility: Reversible shorts (like the Swim 5" Reversible Board Short or Swim 4.5" Reversible Short) give you two looks in one – great for travel. Standard styles are simpler but may lack that flexibility. If you pack light, a reversible short is a smart choice.
Product facts
- Swim 5" Reversible Board Short - Melting Rainbow: Two looks with one swimsuit. Reversible boardshorts are almost impossible to find, which is why we took on the challenge! The new 5” Reversible Board Short is our answer to your request for a shorter inseam. They’re effortlessly versatile and can be worn as swim board shorts, a coverup, and an activewear short. This short gives you two colorways in one, saving packing space and letting you switch up your look without carrying extra gear. The 5-inch inseam strikes a balance between coverage and freedom of movement.
- Swim 7" Pull-On Board Shorts Light Weight - Marine Mosaic: This pull-on swim trunk is unlined, with no closures, no zippers, no hardware, and a fully elastic waistband—aka easy to get into and made with minimal dexterity in mind. Pull up, jump in, and get on with your (sun)day. Sustainability note: We recycle 7 water bottles to make each 7” board short. If you value simplicity and ease, this unlined trunk with an elastic waistband is a no-fuss option. It's also a sustainable choice, using recycled materials. The 7-inch inseam offers more coverage and a relaxed fit.
Which one is right for you?
Best for
- Active swimmers who want a shorter, sportier cut that dries fast and reduces drag.
- Travelers who want a reversible short that works as both swimwear and casual shorts.
Not for
- Anyone who prefers a longer, more modest silhouette with extra coverage – choose board shorts instead.
- People who need pockets and a lace-up fly for a classic surfer look – board shorts are the better fit.
