How Do I Find My Size in Coats? A Stylist's Guide to Getting It Right First Time

By Ella Blake, Tellar Stylist

Finding your size in coats is actually simpler than most people think — and the answer starts with your bust measurement. Unlike a dress or a top, a coat needs to fit across the shoulders and close comfortably over whatever you're wearing underneath. Get those two things right, and you're most of the way there.

I've had my fair share of coat disasters. My absolute worst was ordering a beautiful camel wool coat from a brand I loved, going on my usual dress size, and receiving something that fit perfectly across the hips — but could not do up over a chunky knit. I looked like I was wearing someone else's coat. I've also done the opposite and sized up so much for layering room that the shoulder seams were halfway down my arms. It looked ridiculous and I felt frumpy all winter. Lesson learned: coat sizing is its own art form.

Here's everything you need to know.

Start With Your Measurements — Not Your Regular Clothes Size

This is genuinely the most important step, and the one most of us skip. Your size in coats can easily be one, sometimes two, sizes up from your regular dress size — and that's completely normal. Coats are structured, often lined, and designed to layer. Here's what to measure:

Bust: Measure around the fullest part of your chest. This is your most critical coat measurement.
Shoulders: If you can, measure from shoulder point to shoulder point across your back. This determines whether a coat will look polished or slouchy.
Waist & hip: Less critical for most coats, but important for belted or fitted styles like a trench.

Once you have your bust measurement, check the individual brand's size guide — because coat sizing varies enormously between retailers. A 14 in Hobbs fits completely differently to a 14 in H&M. That's not a flaw, it's just the reality of fashion.

Allow for Layering — It Really Does Matter

This is where people go wrong most often. Try your coat on (or size it) with the kind of layers you'll actually wear underneath it. A thin shirt? Fine, your usual size probably works. A thick roll-neck or a padded gilet? You'll likely need to go up. Ask yourself honestly: what will this coat live over? If the answer is chunky knitwear from October to March, factor that in from the start. The time I ruined Christmas was failing to do exactly this.

The Shoulder Fit is Non-Negotiable

Even if a coat buttons up perfectly, if the shoulder seam is sitting off your actual shoulder — either hanging down your arm or straining upwards — it won't look right and it won't sit well. The shoulder seam should land right at the edge of your shoulder bone, full stop. You cannot really tailor this. If the shoulders don't fit, the coat doesn't fit. This is the one place I always say: do not compromise.

High Street Brands: What to Know About Their Sizing

Sizing is inconsistent even within the same brand season to season, so I always recommend checking fit notes or reviews before buying online. That said, here's a quick rundown of where I'd head for coats this season:

Reiss — beautifully tailored, tends to run true to size. A reliable first stop for a sharp wool coat. Great for classic cuts.
Massimo Dutti — excellent quality for the price point, consistent sizing, and they do some of the best camel tones on the high street.
Whistles — cut generously through the bust, which is great if you're fuller on top. Their coats photograph beautifully too, which never hurts.
Cos — architectural cuts with a Scandinavian edge. Sizing is usually consistent but the silhouettes are deliberately oversized, so try in store if you can before buying online.
Me&Em — British brand doing exceptional outerwear. Slim through the shoulder so if you're broad, consider sizing up. The quality is outstanding for the price.
Phase Eight — one of the best for women who want a coat that actually fits a curvier frame without going boxy. Their size guides are reliable.
Jigsaw — a personal favourite. Slim fits but quality fabric, and their online size guide is one of the more accurate ones I've come across.
Hobbs — classic, well-made coats that sit beautifully. Size tends to run slightly small through the bust, so I'd go up one if you're between sizes.

Premium & Designer: Worth Knowing Before You Buy

If you're investing in a premium or designer coat, the sizing rules become even more important — you really don't want to be returning a £600 coat.

Max Mara — the gold standard of coat dressing. They size in Italian sizing (so a UK 12 is roughly a 44). Always check and always try on if you can. The Teddy coat runs large.
Ted Baker — uses its own sizing system (0–5 rather than 8–18), which trips people up constantly. Check the measurements on their site rather than going by the number.

Two Independent Brands Worth Discovering

I always want to shine a light on smaller brands doing brilliant things:

Harly Jae — a Canadian-founded, London-loved brand making incredibly chic oversized coats with a modern edge. Consistent sizing and brilliant customer reviews. Worth seeking out.
Izabel London — an underrated independent label with a great range of affordable coats. Detailed size information on their site and they photograph their pieces on multiple body types, which is genuinely helpful.

Quick Tips Before You Buy

Always measure your bust before ordering a coat online
Read customer reviews specifically for fit notes — "runs small", "generous shoulders" etc.
If you're between sizes, go up — you can always wear a slimmer layer but you can't add room
Try on in store whenever possible, especially for investment pieces
Check the lining — a well-lined coat layers better and feels completely different to wear

Never Guess Your Coat Size Again — Try Tellar

This is exactly the kind of problem Tellar.co.uk was built to solve. Tellar is the UK's leading free sizing tool — matching your body measurements to over 1,500 brands instantly. Enter your measurements once, and Tellar tells you your precise size across every brand, from COS to Reiss to Max Mara. No more guessing, no more returns.

Use the Store Size Lookup tool to find your exact size in any coat brand right now — it's free, works in-browser, and requires no download or sign-up.

And while you're there, explore the Tellar Fashion Hub — a free library of style guides written by real stylists. Honest, independent, and never sponsored. Some reads I'd recommend alongside this post: