Hiking fleeces and midlayers: reviews and buying guide

What a fleece and a midlayer actually do

The fleece, or midlayer, is the layer that manages your temperature on a walk. Your base layer moves sweat off your skin, your shell keeps the weather out, and the layer in between traps the warm air your body makes while still letting that moisture pass through to escape. Get it right and you barely notice it. Get it wrong and you spend the day either boiling on the climbs or shivering the moment you stop.

For our ranked picks by type, from the best all-round midlayer to the warmest fleece and the best budget buy, see the best hiking fleeces roundup. There is also a women's fleeces and midlayers guide.

Fleece or midlayer: what is the difference?

The two words are often used for the same thing, and mostly they are. A fleece is a knitted or brushed polyester fabric that traps air in its pile. A midlayer is the broader job: any layer worn between your base and your shell for warmth. Most midlayers are fleeces, but not all. Active-insulation pieces, the ones built around PrimaLoft or Polartec Alpha, use a light synthetic fill instead of a fleece pile to give more warmth for the weight while still breathing when you move. We cover both here, because for a UK hiker they do the same job in the layering system.

Grid, high-loft and solid fleece

Fleece comes in three broad types, and the type matters more than the brand. A grid fleece has a waffle-like inner face that traps warm air in the squares while the channels between them dump heat and moisture fast, which makes it the breathable one you wear while working hard. A high-loft fleece has a deep, plush pile that holds a lot of air, so it is the warm one you pull on when you stop. A solid, flat-faced fleece sits between the two: cosy and cheap, warm at rest, but heavier for its warmth and less breathable on the climb. Most walkers are best served by a grid fleece for everyday use, with a high-loft fleece added for cold, low-output days.

Fleece fabrics explained

A few fabric names come up again and again. Polartec Power Grid is the benchmark grid fleece, light and breathable with a gridded back. Polartec Thermal Pro covers the warmer, higher-loft fabrics. Polartec Power Stretch is a close-fitting, stretchy, more wind-resistant fleece with a smoother face, good as a slim technical layer. PrimaLoft and Polartec Alpha are active insulations rather than fleeces, giving warmth for very little weight. Own-brand fabrics from Rab, Montane and Mountain Equipment are often close equivalents of these, so judge a fleece on its type and weight rather than the marketing name.

How to choose: warmth, weight, fit and features

Start with the job. If you want one do-everything layer for changeable UK days, a grid fleece or a light active-insulation midlayer is the versatile choice. If you feel the cold when you stop, add a high-loft warm fleece rather than buying one heavier fleece that is too warm to walk in. Beyond that, a hood adds real warmth and wind protection for very little weight, a deep chest or full zip lets you dump heat fast, and a slim cut layers more cleanly under a shell. Weight and packability matter if you carry the fleece more than you wear it. Fit matters most of all, because a fleece only traps air well when it sits close without being tight.

How to wash and care for a fleece

Fleece is easy to look after and lasts for years if you treat it right. Wash it inside out on a cool, gentle cycle with a liquid detergent, and skip the fabric softener, which clogs the pile and kills the warmth and breathability. Never tumble dry it on heat and never iron it, because fleece is polyester and will melt. To slow down pilling, do up the zips and wash it with smooth fabrics rather than rough hook-and-loop straps. A well cared-for fleece will outlast several waterproofs.

Where a fleece sits in your layering system

Think of your layers as a system, each with one job: base layer for moisture, fleece or midlayer for active warmth, insulated jacket for standing-still warmth, and a shell for the weather. A fleece is neither waterproof nor windproof, so it works best under a shell when the weather turns, not instead of one. In deep cold it is one part of the stack rather than the whole answer: below a certain temperature you add a down or synthetic jacket over the top for the standing-still warmth a breathable fleece cannot give.

For the layers either side of the fleece, see our base layers guide and waterproof jackets guide.