Shoulder seams should sit at the natural edge of your shoulder with no overhang or pulling. The jacket should follow the line of your chest and waist without pulling at the button and without excess fabric sitting loose at the sides. Sleeve length should finish at the wrist bone, allowing approximately 1cm of shirt cuff to show when wearing a collared shirt underneath. If the shoulders fit, most other adjustments can be made by a tailor.

Chest measurement is the primary sizing reference for men's blazers. Measure around the fullest part of your chest with the tape sitting flat across your shoulder blades, keeping it level and snug without pulling tight. If you sit between sizes, size up and have the jacket taken in rather than buying too small and restricting movement. Full size guidance is available in the Barkers fit guide.

An unstructured blazer is built without the internal canvas, shoulder padding and heavy lining found in formal suit jackets. The result is a softer, lighter jacket that drapes more naturally and feels closer to a casual layer than a formal garment. Unstructured blazers are the most comfortable option for everyday and casual wear, and work particularly well in linen and lightweight cotton fabrics during warmer months.

A suit jacket is part of a matching set and is designed to be worn with coordinating trousers from the same fabric. A blazer is a standalone piece, most commonly in solid navy, grey or neutral tones, built to be paired with contrasting trousers or denim. A sports coat sits further toward the casual end, typically featuring textured fabrics and patterns. For a full breakdown of all three, see the Barkers guide to suit jackets, blazers and sports coats.

No. An unstructured blazer in a casual fabric like linen or cotton worn open over a tee and jeans is no more formal than a casual jacket. The key is fit and fabric. A well-fitted linen or unstructured cotton blazer worn casually reads as considered rather than overdressed. The structure of a blazer lifts an outfit without demanding the full formality of a suit.