Flannel Suits: Worsted vs Woolen Flannel and When to Wear Them

A gray flannel suit is the cold-weather partner to the navy worsted: soft where the worsted is crisp, warm where it is cool, and quietly textured rather than smooth. It became shorthand for the American office worker after Sloan Wilson's 1955 novel The Man in the Gray Flannel Suit, filmed in 1956 with Gregory Peck. Flannel is also widely misunderstood, because the word covers two quite different fabrics: woolen flannel and worsted flannel. Knowing which is which decides how warm the suit will be, how it wears and when you can wear it.

What is flannel?

Flannel is a wool fabric, usually a plain weave or a twill, that is finished to raise a soft surface. After weaving, the fabric is milled, washed and worked so the fibers shrink and lock together slightly, and then napped, or brushed, so loose fibers stand up from the face. The result is a matte, slightly fuzzy surface that partly or fully hides the weave.

Fabrics of this kind were well known in Wales by the 16th century, and flannel making spread to England and beyond over the following centuries. In England, one of the best-known flannel weavers, Fox Brothers of Wellington, Somerset, has been making fabric since 1772.

What is the difference between worsted and woolen flannel?

The difference starts with the yarn. Woolen flannel is woven from carded yarn, in which the fibers lie in every direction. The yarn is spun loosely, and the fabric is milled and brushed until the weave all but disappears, so it is soft, lofty and warm. Worsted flannel is woven from combed yarn, in which long fibers lie parallel. It is milled more lightly, so you can often see a faint twill under the nap, and it feels smoother, firmer and cooler. Our guide to worsted vs woolen wool explains the two spinning systems.

What weight should a flannel suit be?

Weight decides how warm a flannel is and how well it hangs. Heavier flannels drape beautifully and keep their shape between pressings. Lighter flannels are easier to wear in heated offices and mild winters, but they crease a little more and lose some of the fabric's softness.

As a starting point, choose a woolen flannel of about 13 to 15 oz (400 to 470 g) if you live with real winters, and a worsted flannel of about 11 to 12 oz (340 to 370 g) if your winters are mild or your office runs warm. The heaviest flannels, around 19 to 20 oz, are made for suits and light coats in serious cold.

When should you wear a flannel suit?

Flannel is an autumn and winter fabric. In a temperate climate, a woolen flannel earns its keep from roughly October to March in the northern hemisphere, and a worsted flannel stretches a few weeks either side. It is too warm for summer, even in air-conditioned offices, because the air trapped in its yarn and nap holds heat. If you live in a hot climate, treat flannel as a suit for winter trips rather than one for home.

What colors are best for a flannel suit?

Gray is the classic, and for good reason: flannel's soft nap gives mid-gray and charcoal a depth that smooth worsteds lack. Mid-gray is the most versatile, at home in an office and relaxed enough to split into separates. Charcoal is the dressier choice for business and evening. Navy flannel is a strong winter alternative to a navy worsted, and brown flannel suits weekends and relaxed offices. Lighter grays read as less formal than darker ones.

The classic pattern is the chalk stripe: a soft, slightly blurred stripe, more widely spaced than a pinstripe, that looks as if it were drawn with tailor's chalk. A navy or charcoal chalk stripe flannel is one of the great winter business suits. Glen checks and windowpanes also suit flannel well.

How do you style a flannel suit?

Flannel's soft surface pairs best with fabrics that have some texture of their own. Choose shirts in poplin, twill or oxford rather than shiny weaves, and ties in wool, cashmere, grenadine or matte printed silk. Black calf shoes suit charcoal and business wear; dark brown calf or brown suede suit mid-gray, brown and weekends.

• Business: charcoal or chalk stripe flannel, a white or blue shirt, a dark tie and black oxfords.
• Smart casual: mid-gray flannel with a roll-neck or a knitted polo in place of a shirt and tie.
• As separates: gray flannel trousers are among the most useful trousers you can own, with a navy blazer, a tweed jacket or a cashmere sport coat. See navy blazer combinations.
• The jacket alone: a flannel suit jacket can work as an odd jacket with cords or dark jeans, because its matte surface already looks like a sport coat.

How should a flannel suit be made?

• Canvas construction. Woolen flannel shapes beautifully under a tailor's iron, and a canvassed chest makes the most of it; see fused vs canvas.
• A full lining. Unlike a summer suit, a flannel suit benefits from a full lining, which adds warmth and helps the jacket slide over knitwear.
• Trousers that hang well. A clean, slightly fuller leg suits the fabric's softness, and cuffs add weight that helps the trousers hang; see trouser cuffs.
• An extra pair of trousers. Woolen flannel wears first at the seat and inner thighs, so a second pair greatly extends the suit's life.

How do you care for a flannel suit?

For more, see how to care for a suit and how to store suits long term.

Flannel suit checklist

A flannel suit is the most comfortable way to wear tailoring in cold weather, and a gray one goes with nearly everything you already own. Add it as your second or third suit, after a year-round worsted, and you will reach for it all winter. For more outfit ideas, see gray suit combinations.

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