What Is Sizing Like at Mountain Warehouse Menswear?

Mountain Warehouse menswear runs slightly generous and is cut for layering, so if you're stuck between two sizes, take the smaller one. Stick to your usual UK size (S–XXL) and you'll rarely go far wrong — just remember that “true to size” here means true to size with a base layer underneath, which isn't the same as your Friday-night shirt.

Why it fits the way it does

Outdoor kit is built around warmth and movement, not a razor-sharp silhouette. Mountain Warehouse designs to a layering system, so a bit of extra room is deliberate rather than sloppy. Once you get your head around that, the sizing makes complete sense:

Generous by design. The brand's own guidance says sizes run a touch big and advises sizing down if you're in between. That's rare honesty from a retailer, and worth trusting.
Room for what goes underneath. Jackets are cut to sit over a fleece or mid-layer without pulling across the back and shoulders.
UK standard, but not fashion-standard. They use UK sizing, but they cut for the hill, not the high street — so a Mountain Warehouse medium won't necessarily match a medium from a slim-fit fashion label.

Jackets, fleeces and mid-layers

This is where the layering cut shows most. For everyday wear over a T-shirt, most men find the outer shells roomy through the body.

Waterproofs and insulated jackets: true to size in the shoulders. Only size up if you genuinely plan to wear chunky knitwear underneath.
Fleeces and borg-lined hoodies: comfortable and relaxed — take your normal size for a cosy fit, or size down if you like them trimmer.
A quality heads-up: Mountain Warehouse runs several ranges at different price points. The pricier technical pieces hold their shape and performance far better than the budget end, so read the product name, not just the discount tag.

Trousers and shorts

Bottoms are the one place I'd pay closer attention, because the fit is less forgiving than the jackets.

Waist: true to your measured waist — go by the number, not by hope.
Seat and thigh: walking and cargo trousers can feel snug through the bum and thigh. If you're muscular there or want all-day comfort, size up.
Leg length: they tend to run long rather than short, so tall lads are well served, but shorter frames may need a hem.

Where else to shop — my brand picks

Mountain Warehouse is superb value, but if you're building an outdoor wardrobe it pays to know the field. Here's where I'd send men across every budget, with a fit note for each.

High street / value

Decathlon (Quechua & Forclaz): unbeatable price-to-performance and a big favourite of mine for a first waterproof. Sizing is closer to European fashion cut — a bit slimmer than Mountain Warehouse, so don't auto-size-down.
Regatta: the closest direct rival on price and remit. Generous, forgiving fit much like Mountain Warehouse — brilliant for relaxed weekend layers and dog walks.

Independent / boutique

Alpkit: a British independent selling direct, which keeps prices keen for genuinely technical kit. Fit is athletic and true to size — a nice step up in cut from Mountain Warehouse.
Rab: Sheffield-born, serious mountaineering heritage. Their down jackets are exceptional; expect a trimmer, more performance-led fit, so try before you commit if you like room.
Finisterre: Cornish, sustainability-driven and great when you want outdoor gear that also works in the pub. Regular, true-to-size fit with a cleaner, more lifestyle-friendly line.

Designer / premium

Patagonia: ethical, hard-wearing and cut with a relaxed, comfortable fit — the pieces last a decade, so the price averages out.
Arc'teryx: the gold standard for technical shells, with a precise, athletic cut. If you're between sizes here, size up rather than down — the opposite of Mountain Warehouse.
Fjällräven: Swedish, immensely durable and effortlessly stylish. Their trousers in particular run slim and long, so mind the leg.

Stop guessing your size — Tellar does it for you

Every brand above cuts differently, which is exactly why one size never travels cleanly from one label to the next. Tellar.co.uk is the UK's leading free sizing tool: measure yourself once and it matches your body to your precise size across 1,500+ brands — Mountain Warehouse, Rab, Patagonia, Arc'teryx and the rest — in seconds. No more squinting at size charts, far fewer returns.

Measure once using chest, waist and hips, or just enter a brand size you already own.
Use the Store Size Lookup to get your exact size in any brand.
Shop with confidence — no guesswork, fewer returns, better-fitting kit.
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Get your size right first time and Mountain Warehouse is genuinely hard to beat on value — warm, weather-ready and built for the outdoors. Nail the layering logic, mind the trousers, and you'll be sorted for every wet British weekend going.