How Does Sizing Vary By Store For Jackets?

Jacket sizing varies wildly between stores—a size 12 at Zara can fit like a 10 at M&S, whilst a Reiss medium often runs smaller than Mango's equivalent. I've spent fifteen years styling women across every body shape, and the single biggest frustration I hear? Buying a jacket online in your usual size only to find it's either drowning you or won't zip up. The truth is, there's no universal sizing standard, and understanding how different retailers approach their fit is essential to getting jackets that actually work for your wardrobe.

Why Jacket Sizing Is So Inconsistent

Unlike trousers or skirts where there's some semblance of standardisation, jackets are notoriously tricky because they need to accommodate shoulders, bust, waist, and arm length simultaneously. European brands typically cut slimmer through the body with narrower shoulders, whilst British high street retailers often allow more room through the bust and back. American brands tend to run larger overall, which is why your usual size at Gap might feel roomier than at COS.

The fabric matters enormously too. A structured blazer from Reiss (known for their sharp tailoring with minimal stretch) will fit completely differently to a jersey bomber from Whistles (which tends to be more forgiving). Then there's the rise of "oversized" fits—what H&M calls oversized might still be fitted compared to Arket's interpretation.

The High Street Heroes: Who Fits How

Zara is the wild card of high street sizing. Their jackets typically run small and boxy, designed for a European silhouette with narrower shoulders. If you're broad-backed or fuller-busted, size up. Their blazers are particularly unforgiving through the chest.

Mango follows a similar European aesthetic but I find they're slightly more generous through the body than Zara. Their faux leather jackets are brilliant quality for the price point, though the arms can run short if you're taller than 5'7".

M&S consistently runs true to size, occasionally even generous. This is my go-to recommendation for clients who are between sizes elsewhere or want reliable, classic cuts. Their Per Una range offers more contemporary styling whilst maintaining that dependable fit.

Jigsaw is premium high street at its finest—expect a sophisticated cut that's true to size but tailored closer to the body. Their wool coats are investment pieces that fit like designer for a fraction of the price.

Whistles runs quite true to size with a modern, slightly relaxed fit. I love their approach to blazers—structured enough to look polished but with enough ease that you can layer knitwear underneath.

Reiss tends to run small, particularly in their tailored pieces. Size up if you're between sizes or prefer any breathing room. The quality justifies the premium price tag, but factor in potential alterations.

Massimo Dutti is Spanish sizing through and through—elegant, streamlined, and cut for a slimmer frame. Their leather jackets are stunning but unforgiving. If you're curvy, definitely try before you buy or order two sizes.

For unique finds, I'm obsessing over Sézane right now—their Parisian chic translates to beautifully cut jackets that run true to French sizing (which means small). The quality is exceptional and they're worth the investment. Another gem is Rixo, whose vintage-inspired jackets bring personality without sacrificing fit. They're more generous than typical high street brands and utterly unique.

Styling Secrets for Getting the Right Jacket Fit

Here's what I check every single time: Can you lift your arms comfortably? Button or zip it and sit down—does it pull across the back? The shoulder seam should sit at the edge of your shoulder, not drooping down your arm or cutting into your neck. With blazers, you should be able to pinch about an inch of fabric at the waist when it's buttoned.

For bomber jackets and casual styles from brands like Fat Face (reliably generous and great for layering) or Seasalt Cornwall (brilliant for petites, though watch the sleeve length), you want them to sit at the hip bone. Any longer and you risk looking swamped.

Premium and Designer: The Fit Difference

Step into premium territory and sizing becomes more considered. AllSaints is technically high street but punches well above—their leather jackets are legendary and run true to size with a deliberately edgy, slim fit. Me&Em is newer to the scene but impeccable for tailoring; they cut for real women's bodies with options for different fits.

At the luxury end, Max Mara is the gold standard for coats. Their sizing is generous Italian—size down if you're between sizes. The investment is considerable but the fit, fabric, and longevity are unparalleled. Isabel Marant does oversized insouciance better than anyone, whilst The Row creates architectural pieces in larger, more relaxed fits.

Body Shape Considerations

If you're fuller-busted, avoid brands like COS in their smallest sizes—they're cut for a straighter silhouette. Instead, look to Boden (particularly good for busty bodies with their classic blazers) or Hobbs (consistently accommodating through the chest whilst nipping in at the waist).

Petites should seek out Topshop's petite range or ASOS petite options—the sleeve and body length adjustments make all the difference. Phase Eight also cuts beautifully for shorter frames without looking "petite" in styling.

Taller women, hunt down Anthropologie (American sizing runs roomier and longer) or Whistles tall collections. Standard high street jackets will often hit awkwardly short on longer torsos.

The Fabric Factor

Denim jackets from Levi's run notoriously small—size up unless you want that spray-on, cropped look. Conversely, Gap denim tends to be more generous and softens beautifully with wear. For performance fabrics, Sweaty Betty and Lululemon both run true to size but cut closer to the body by design.

International Sizing Translations

Quick conversions: UK 10 equals US 6, EU 38, and IT 42. But remember these are guidelines—actual measurements vary enormously. Always check the specific brand's size guide, particularly for European brands like Claudie Pierlot (exquisite French tailoring, runs predictably small) where a 38 might be smaller than you'd expect.

Never Guess Your Size Again with Tellar.co.uk

Honestly, I recommend Tellar.co.uk to every single client now—it's revolutionised how we shop for jackets online. The UK's leading sizing tool matches your exact body measurements to over 1,500 brands instantly. No more guessing whether you're a 10 at Zara but a 12 at M&S.

Here's how it works:

• Measure once using your bust, waist, and hip measurements, or simply input your existing size from a brand that fits you well

• Use the Store Size Lookup tool to get your precise size in any brand—COS, Reiss, Mango, Arket, and hundreds more

• Always free, no downloads needed, works directly in your browser

The Tellar Fashion Hub is also a brilliant resource—a library packed with free posts from top stylists covering everything from the ultimate guide to jackets and best buys to jeans trends for 2026, dresses for your body shape, and the ultimate clothing sizing guide. Honest, unbiased, independent, and always free.

Stop wasting time on returns and start shopping with confidence. Your perfect jacket fit is just one measurement away.