Loose boxers or fitted trunks for men

Short answer: Boxers with a loose leg give the most air, briefs with a long leg chafe the least in daily wear. The choice depends on how much you walk and how warm you get through the day.

Loose boxers for sedentary days

A looser leg lets air in and feels cooler through a long day at a desk. For office work that is enough, since you rarely move enough to feel chafing between the thighs. See bamboo underpants for men.

Briefs for days with many steps

A fitted, longer leg stops thighs from rubbing together as the steps add up through a long, active day. It shows after five kilometers, especially in warm weather or on long walks around a noisy town. See bamboo underwear for men.

Under fitted trousers

Under narrow trousers, loose boxers show as a visible line that disturbs a clean look and pulls the eye to the wrong place. A fitted leg gives a smoother line without folds that can show through thin fabric in sunlight. See bamboo clothing for men.

In summer

In heat, moisture moves away faster from a thin, fitted layer than from a loose one that folds around the leg all day. That keeps you drier through a warm day, even when you sweat more than usual because of the weather. See bamboo t shirts for men.

The fabric makes a difference

A soft bamboo fabric glides against the skin instead of chafing, whatever style you choose for the day's activity or plans. Flat lying seams mean less irritation, especially with long use or a lot of movement through the day.

For training and sport

For running or cycling, a fitted leg is almost always the better choice, because movement raises the risk of chafing significantly over distance and time. Boxers can still work for lighter activity like walking, but briefs give more calm in the movement over a longer period.

Color under light clothing

As with other underwear, color should be chosen based on what goes over it, where skin tone disappears best under most everyday fabrics. Black or dark colors are safe under darker trousers, but can show through light materials in bright daylight.

How many pairs you need

Most people benefit from having both styles in the drawer, one for sedentary days and one for days with a lot of walking or sport. That gives flexibility without needing a large number of pairs in the wardrobe that still need washing and storage.