What to wear under a sports jacket

What you wear under a sports jacket (also called a sport coat) should balance formality, comfort, and context. The right choice depends on whether the setting is business casual, smart casual, or relaxed social wear.

For business casual and professional settings, the most appropriate option is a button-down shirt. An Oxford cloth button-down, poplin dress shirt, or subtle patterned shirt maintains a clean, structured appearance and works naturally with the tailored silhouette of a sports jacket. Light colors such as white, light blue, or pale grey are the safest and most versatile.

A fine-gauge sweater is another excellent option, particularly in cooler weather. Crewneck or V-neck sweaters in merino wool, cashmere, or cotton blends layer smoothly under a sports jacket without adding bulk. This combination looks polished while remaining relaxed, making it ideal for offices with flexible dress codes.

For smart casual environments, a knit polo or classic polo shirt works well. The collar adds structure, while the knit construction softens the overall look. Neutral or muted colors keep the outfit refined rather than sporty.

In more relaxed or modern workplaces, a plain T-shirt can be worn under a sports jacket, but only if done carefully. The T-shirt should be high quality, well-fitted, free of graphics or logos, and in a solid neutral color such as white, black, or navy. This pairing leans casual and is not suitable for formal or client-facing situations.

A turtleneck or mock neck is a strong option in fall and winter. It creates a clean, contemporary look and pairs especially well with textured or wool sports jackets. This choice works best in creative, fashion-forward, or European-style settings.

Items generally not recommended under a sports jacket include hoodies, tank tops, graphic tees, athletic wear, and thick or bulky knits. These disrupt the jacket’s structure and lower the overall level of polish.

In summary:

• Button-down shirts and fine sweaters are the most versatile and professional

• Polos and knitwear suit smart casual settings

• Plain T-shirts and turtlenecks work only in relaxed or modern environments

The safest rule is simple: the more structured and minimal the layer underneath, the better it will complement a sports jacket.