The Warmest Jumpers, Compared: Which Knit Traps the Most Warmth

Key takeaways:

• Warmth is trapped air: the thicker and more textured the knit, the more still air it holds against the body — that, not the fibre name alone, is what warms you.
• Chunky rib and cable lead: deep structures (£59 each in our range) hold the most air per layer.
• Coverage is the second mechanism: a roll neck warms the place a crew neck leaves open, and a vest under a coat warms the core without sleeve bulk.
• No honest warmth rating exists: any listing that grades jumpers by degrees is inventing it — buy on structure, weight and layers instead.

WARDLEY London is our own store — prices and product facts below are taken from our own listings.

What actually makes one jumper warmer than another?

Still air. A knit warms you by holding a layer of air against the body and stopping it moving; the deeper the structure — ribs, cables, brushed surfaces — the more air it holds. Fibre matters second: wool and wool blends insulate well and manage moisture, synthetics insulate by loft and dry fast, cotton is comfortable but the least insulating of the three when it is cold and damp. Judge a jumper by its structure first and its composition line second, and be suspicious of any warmth claim that comes with a number attached. What follows compares the four structures in our range on that basis — all four are £59, so structure is the only variable.

Chunky rib: the most air per layer

The Limehouse Fisherman Rib (£59) is the deepest structure we sell — a chunky rib knit, 100% polyester, in a relaxed fit with a dropped shoulder. The ribs stand proud of the surface, the loft is high, and as a single layer on a cold day it is the warmest jumper in the range. The relaxed cut is part of the mechanism: air needs room to sit still, and a relaxed knit over a base layer traps more of it than a tight one.

Cable knit: texture with a closer fit

The Cotswold Cable Knit (£59) carries its texture in raised cables over a slimmer cut — less loft than the fisherman rib, but a cleaner line under a coat, which is where most winter warmth is actually decided. Its cloth is a polyester, nylon and viscose blend, stated on its page. For the same texture without sleeves, the Harrow Cable Vest (£59) layers over a shirt under a jacket — core warmth, no bulk at the arms.

Brushed knit: the raised surface

The Mortimer (£59) is a brushed, mohair-look knit: the brushing raises fibres from the surface, and that raised nap holds air the way a fleece does. It reads softer and less structured than the rib or the cable — the warmest-feeling of the four against the skin, and the one to choose for evenings and slow days rather than weather.

The roll neck: warmth by coverage

The Marylebone Roll Neck (£59) is a fine ribbed knit — on structure alone it would rank last here. It earns its place by coverage: the neck is where a crew neck leaks heat and where a scarf is not always worn, and the roll neck closes it while layering cleanly under an overcoat. Worn under a coat, the fine knit plus coverage outperforms a chunkier knit worn alone in wind. Our layering guide builds whole outfits on that principle.

So which should you buy?

For a single jumper against the cold: the Limehouse. For warmth that has to fit under a coat: the Cotswold, or the Marylebone where the neck gap is the problem. For comfort indoors and out: the Mortimer. And for the coldest days, stop asking one jumper to do the whole job — the layers-by-temperature guide sets out what to add, and when. The full range is in men’s knitwear.

The Black Friday note

Until Sunday 29 November 2026, 23:59, two items in a basket take 15% off automatically and three or more take 25% off — no code. Free tracked UK delivery on every order; dispatched in 1–2 working days, with delivery 6–10 working days from order, and 30-day returns.

Frequently asked questions

Is a thicker jumper always warmer?

Almost always, worn alone — thickness is loft, and loft is trapped air. Under a coat, a slimmer textured knit can be the warmer system because the coat adds the outer layer.

Does the fibre matter at all?

Yes, second. Wool blends manage moisture best in active use; synthetics hold loft and dry fast; cotton is the comfort choice and the weakest insulator. Each product page states its composition — read it there, not here.

How do I wash the warm ones?

Per the garment’s own instruction, and generally as our knitwear care guide sets out: gentle wash, dry flat, fold to store.