What Is Sizing Like at Montane?

Montane runs largely true to size, but here's the catch most people miss: the fit you get depends entirely on which fit category the garment belongs to, not just the letter on the label. A Montane medium is not a single fixed thing – it shifts depending on whether the piece was built to sit next to your skin or layer over a fleece on a freezing ridgeline. Once you understand that, sizing Montane becomes genuinely easy. Get it wrong, though, and you'll end up with a baselayer flapping like a sail or a shell you can't zip over a jumper.

I learned this the slightly embarrassing way. I bought a Montane Prism in my usual size years ago, wore it as a standalone jacket all autumn, and couldn't work out why it felt a touch generous – until a hiking friend gently pointed out it was designed to be layered over a midlayer. Different game entirely. So let me save you the faff.

The short answer

If you wear a standard UK 12, you'll almost always be a Montane Medium. The brand sizes cleanly from XXS to XXL and the body measurements are consistent and honest – no vanity sizing, no nasty surprises. What changes is the cut, and that's where you need to pay attention.

Montane's fit categories – the bit that actually matters

Montane engineers every piece around its intended activity, then files it under a named fit. For your upper body you'll see:

Expedition & Mountain fit – roomier, built to layer over insulation. Think shells and big winter pieces.
Regular fit – the everyday middle ground, comfortable without being baggy.
Trim fit – close to the body, for fast-moving activity and baselayers.

Legwear follows the same logic, running from Regular and Athletic through to Trim, Run and Next-to-Skin. The golden rule: keep your fit category consistent across your layers. A Medium Mountain-fit midlayer wants a Medium Mountain-fit shell over it. Mix categories and the system stops working.

How it actually sizes in real life

Outer shells run roomier – that's deliberate. Don't size down to make a waterproof feel snug; you'll regret it the first cold day.
Insulated pieces are more fitted – the Prism and similar synthetic-insulated styles sit closer. Lovely as a midlayer, just remember they're cut for layering.
Baselayers are close and true – take your normal size; they're meant to hug.
Trousers run long in the leg – brilliant news if you're tall, but most have adjustable or articulated hems regardless. The award-winning Terra trousers are a classic example.
Arms are generous – a recurring theme in reviews. Great for reaching and climbing, occasionally a touch long if you're petite.

My styling advice

Buy for the job the piece is meant to do. If a jacket is your only outer layer for dog walks and the school run, a Trim or Regular fit will look far sharper than a billowing Mountain shell. If you're a proper hill walker building a layering system, stay loyal to one fit category and one size the whole way up. And always measure your bust, waist and hip rather than trusting the size you think you are – Montane's measurements are precise, so they reward precision back.

Where to shop – and brilliant alternatives

High street: For everyday active and outdoor-casual pieces that pair beautifully with technical kit, Gymshark nails affordable, body-skimming activewear, while Superdry does genuinely capable technical jackets at a friendlier price. For that coastal, throw-on-and-go look, Seasalt Cornwall and Fat Face are unbeatable, and Joules brings proper British country charm to your off-mountain wardrobe.

Premium: If you want performance with polish, Sweaty Betty is my go-to for leggings and studio-to-trail layers that fit immaculately, and Lululemon remains the gold standard for technical fabric and a flattering cut. For heritage waterproofing with serious style credentials, nothing beats Barbour.

Luxury & independent gems: Here's where I'd nudge you off the beaten track. Finisterre, the Cornwall-born B Corp, makes gorgeously considered, sustainable outerwear that looks as good in town as on the coast path. And for true Montane-level technical credibility, Páramo – a quietly cult British brand – produces some of the most weatherproof, ethically made kit you'll ever own. Both are real insider picks.

Never guess your size again

This is exactly the headache Tellar was built to solve. We're the UK's leading sizing tool – your body matched exactly to over 1,500 brands instantly, so you never have to squint at a confusing size guide again.

Measure once, using your bust, waist, hip, or simply a brand size you already own.
Use our Store Size Lookup tool to get your precise size in any brand – COS, Reiss, Everlane, Arket and many more.
Always free, no downloads, works straight in your browser.

And there's the Tellar Fashion Hub – a library stacked with free posts from our top stylists. Honest, unbiased, independent and always free. Style advice, top picks and the best brands, all in one place.

A few of my favourites to read next:

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