Fleece Buying Guide

Fleece fabric was invented in 1979 by Malden Mills, now known as Polartec, as a lighter stand-in for wool, and it replaced wool jumpers in most hikers' bags within about a decade. The idea behind it hasn't changed since: a knitted polyester fabric that traps air between its fibres and holds heat in without adding much weight, so air pockets do the work rather than thick material.

That basic idea covers a lot of ground, though. Polar fleece, micro fleece, tech fleece and sherpa fleece all trap air the same way, but each one is built differently, and that changes what it's actually good for.

Fleece fabric carries a weight rating in grams per square metre, shortened to GSM. A higher number means more trapped air, so more heat retention and a bit more bulk.

• Lightweight fleece (less than 200 GSM): suits base layers, warmer months and fast-moving days on the hill.
• Midweight fleece (200 to 300 GSM): the most common weight on shop floors, a fair balance for hiking, everyday wear and layering under a shell.
• Heavyweight fleece (300 GSM and above): includes most sherpa styles and thick polar fleece, suited to standing around outdoors or wearing on its own on a proper cold day.

Checking the GSM figure on a label takes seconds and saves guessing between two jumpers that look nearly identical but perform very differently. Browse our full range of fleeces here.

It comes down to three questions: what you'll use it for, what you'll wear it with, and how much room you've got to pack or store it.

The fabric is one choice. Shape and closure is the next.

• Full zip fleece opens all the way down the front. Quick on, quick off, easy to vent on a climb.
• Half zip or quarter zip fleece only opens partway, like a jumper with a short zip at the neck. Less bulk, snugger collar.
• Hooded fleece jacket adds cover for windy days. Works as a stop gap layer when a full waterproof shell feels like overkill.
• Fleece gilet or vest drops the sleeves. Keeps the core warm, leaves arms free for cycling or carrying shopping.
• Fleece cardigan or coatigan sits closer to knitwear, open at the front with buttons or an undone zip.
• Plain fleece pullover or jumper has no zip at all. Usually the simplest, lightest option of the lot.

Fleece holds up well over years of washing, with a little care.

• Wash on a cool cycle. Skip fabric softener, since it coats the fibres and stops fleece from trapping air properly.
• Turn zip-up jackets inside out before washing to protect zips and printed logos.
• Air dry where possible. Tumble drying on low heat is usually fine for polar fleece, but check the label first.
• Run a fabric shaver over any bobbling every few months to keep the texture going strong.

A fleece rarely works alone. It's one part of a bigger system built from a base layer, a mid layer and an outer shell, each doing its own job.

A base layer sits against the skin and moves sweat away from the body. The fleece comes next, trapping heat while still letting that moisture escape. An outer shell, usually waterproof or wind-resistant, goes over the top and takes the brunt of rain and wind. With all three working together, it's much easier to stay warm without overheating, or to strip a layer back the second the sun comes out.

For a full breakdown of how to build a layering system for hiking, skiing or everyday cold weather, read our Layering System Guide.