Twill, Melton, and Flannel: The Classic Suiting and Outerwear Fabric Structures

The character of a wool garment — its texture, its weight, its appearance in light, and how it ages — is determined largely by the fabric's weave structure and finishing. Three of the most important and widely used wool fabric types in tailoring and outerwear are twill, melton, and flannel. Each has a specific visual and tactile quality that makes it appropriate for certain garments and seasons.

Twill

A twill is a fabric woven with a diagonal rib structure — the weave pattern creates diagonal lines visible on the fabric's surface. The familiar herringbone, houndstooth, and tweed patterns are all twill variants, as is the smooth, diagonal-rib face of most smooth worsted wool suiting fabrics.

Twill weaves are notably strong and durable for their weight because the diagonal interlacing of threads distributes stress across more fibres than a plain weave. This makes twill the most common weave structure for suiting fabrics — from the fine, smooth worsted twills of business suiting to the coarser, more visible diagonals of tweed jacketing. The classic herringbone — a chevron pattern created by alternating the twill direction — is the most recognisable twill variant in menswear.

The weight and fibre of a twill fabric determine its seasonal application: a lightweight fine-worsted twill is appropriate for year-round or three-season suiting; a heavy wool-linen twill works for summer jacketing; a coarse woollen twill creates the rustic texture of country tweeds.

Melton

Melton is a heavy, tightly woven wool fabric that is milled and felted after weaving — a finishing process that presses the fibres together, shrinks the fabric slightly, and creates a smooth, dense surface on which no weave structure is visible. The result is a fabric with a characteristic solid, matte face that is highly wind-resistant and retains its shape well under pressure.

Melton is used primarily for overcoats and outerwear — the Chesterfield coat, the guard coat, the pea coat, and the classic British greatcoat have historically been made in melton. Its dense structure keeps wind and light rain out without the stiffness of a coated or waterproofed fabric. The milled surface of melton also cuts cleanly and retains a precise edge — which suits the structured military-derived silhouettes in which it is most often used.

Melton weight is typically measured in grams per running metre rather than the square-metre measure used for lighter suiting fabrics; a standard melton overcoat fabric might weigh 650–800 grams per running metre, compared to 350–450 gsm for a flannel suiting.

Flannel

Flannel is a wool fabric distinguished not by its weave structure (which can be plain or twill) but by its finishing: it is lightly brushed after weaving, raising the surface fibres into a short, soft nap that gives flannel its characteristic matte, slightly fuzzy surface. This brushed nap gives flannel its warmth-to-weight ratio advantage — the raised fibres trap air and add insulation beyond what the fabric weight alone would suggest.

Flannel is the defining suiting fabric of autumn and winter in classic menswear. Grey flannel — in medium to dark tones — is the most versatile suiting fabric for colder months, and the grey flannel trouser is a wardrobe staple that works across jacket combinations from formal suits to casual blazers. See our capsule wardrobe guide for how flannel trousers anchor a formal wardrobe.

The weight of flannel for suiting typically falls between 280 and 380 gsm — lighter enough to make a full suit without excessive warmth, heavy enough to drape well through a long winter day of wearing.

Related terms: super numbers — canvas