Are Board Shorts Swim Trunks? The Difference Explained

Board shorts are swimwear, but they are not swim trunks.

The difference is simple: swim trunks are shorter, have an elastic waist, and almost always include an inner liner. Board shorts are longer, have a fixed waistband with a drawstring or velcro fly, and are usually unlined, because they were built for surfing, not lounging.

If you have ever wondered why the two feel so different in the water, here is the breakdown.

What's the actual difference between board shorts and swim trunks?

The liner is the difference that matters most in practice. Board shorts skip it so the fabric does not bind against a surfboard, which also means they offer zero built-in support. Swim trunks include one, for better or worse; the classic mesh version is its own saga, told in why swim trunks have netting.

Why are board shorts so long and unlined?

Surfing. Long shorts protect thighs from board wax rash, and the missing liner prevents bunching when paddling. The fixed waistband stays put when a wave tries to remove your shorts. Every board short design choice solves a surfing problem. None of them solve a swimming or lounging problem, which is why board shorts at a pool party are a style statement, not a function choice.

Which should you wear?

• Surfing or board sports: board shorts, obviously. It is their home turf.
• Swimming, beach days, pool: swim trunks with a proper liner. Shorter cut moves better in water, and the liner handles support.
• Long beach walks and active days: trunks with a compression liner specifically, because the liner is your anti-chafe layer. The full spec of what to look for is in our compression liner guide.
• Wearing board shorts anyway? Add a quick-dry layer underneath, since unlined shorts plus nothing equals chafing and transparency risks. The layering rules are in do you wear underwear with swim trunks.

Frequently asked questions

Can you swim laps in board shorts?

You can, but the extra fabric drags noticeably. For actual swimming, shorter lined trunks or jammers move much better.

Do any board shorts have liners?

A few hybrid models add a liner, which makes them functionally long swim trunks. Check the product description for "lined" before assuming.

Are hybrid shorts the same as board shorts?

Hybrid shorts are walk shorts made of quick-dry fabric, designed to pass as regular shorts. They are usually unlined like board shorts but cut shorter. Same layering rule applies if you swim in them.

Why do surfers not get chafing without a liner?

They do, from wax and salt, just in different places. Surfers manage it with rash guards, wax choice, and barrier products. On land, walking distance is what turns unlined shorts into a chafing problem.