How to Find Your Size in Blouses

By Ella Blake, Tellar Stylist

To find your size in blouses, you need three measurements: your bust, shoulder width, and sleeve length — because unlike most other clothing, blouses have multiple fit points that all need to line up at once. I know this sounds obvious, but I spent an embarrassing number of years just ordering my usual dress size and wondering why everything either pulled across the back or gaped at the buttons. Blouses are genuinely one of the trickiest categories to size for — and the reason is that every brand cuts them completely differently. Once I started measuring properly and understanding how brands vary, everything changed. Here's exactly what you need to know.

The Three Measurements You Actually Need

Forget just knowing your dress size — for blouses, these are the numbers that count:

Bust: Measure around the fullest part of your chest, keeping the tape horizontal and snug but not tight. This is your most important blouse measurement.
Shoulder width: Measure straight across your upper back, from the edge of one shoulder to the other. This is the measurement most people skip — and it's the one that causes the most returns. If a shoulder seam droops off your shoulder, the whole blouse looks wrong and no tailor can fix it easily.
Sleeve length: From the bony tip of your shoulder down to your wrist. Essential if you're buying anything with a fitted cuff or a proper shirt sleeve.

Save all three in your phone. I have mine in a note alongside my usual brand sizes — it takes about two minutes to measure and it will save you hours of returns admin, I promise.

Understanding Blouse Fit: Why It's So Complicated

The reason blouses are so sizing-chaotic is that they have to fit across your shoulders, through your bust, around your back, and down your arms — all at the same time. Dresses can get away with a bit of looseness. Blouses cannot. A blouse that's slightly off at any one of those points just looks... wrong.

The other complication is vanity sizing. Brands shift their size labels constantly to make customers feel good, which means a size 12 in one brand genuinely is not the same as a size 12 in another. A size 14 in Marks & Spencer — which cuts generously and with a traditional British fit through the bust — is noticeably different to a size 14 in Cos, which runs narrow and lean across the shoulders in that Scandinavian minimalist way. Both are lovely brands. But if you order both in the same size expecting the same fit, you'll be disappointed.

The Bust vs. Shoulder Problem (and How to Solve It)

This is the blouse dilemma I hear about most. Your bust measurement says size 14 but your shoulders need a 12, or vice versa. Here's my practical stylist rule:

For structured, tailored blouses — office shirts, pointed-collar styles, anything with a fitted cut — always size to your shoulders first. You can have a bust taken in by a tailor relatively cheaply. Restructuring a shoulder seam is an entirely different (expensive) job.
For relaxed, unstructured blouses — wrap styles, linen tops, peasant blouses, anything floaty — size to your bust. The shoulder in these styles is less rigid and there's enough movement in the cut to accommodate some variation.

If your measurements regularly fall between sizes or across size categories, it's also worth looking at brands that offer a wider range of fits. Boden is genuinely excellent for this — they flag whether a blouse is relaxed, regular, or fitted, and they're unusually honest about it in their product descriptions. White Stuff also tends to offer a relaxed, forgiving cut that works well if you're fuller through the bust.

How Different Brands Tend to Cut Their Blouses

Here's a quick breakdown of how some of the most popular UK high street brands approach blouse sizing — based on customer reviews, styling guides, and frankly, a lot of personal trial and error:

Marks & Spencer: Generous and traditional. Great for a fuller bust, reliable across sizes. Their linen blouses in particular are consistent year on year.
Cos: Boxy and relaxed. Runs narrow in the shoulder, so if you're broader go up one size. Beautiful for minimalist styles but not for anyone wanting fitted.
Whistles: Tailored but not restrictive. A good middle ground — they're honest about their sizing and include chest measurements on most product pages.
Phase Eight: Cuts for a curvier, womanly figure. Brilliant for a fuller bust and generally very flattering through the waist too.
Reiss: Slim and structured. Size up if you're fuller in the bust or back. Their blouses look exceptional when they fit — very polished.
Hobbs: Smart-casual and consistently sized. A reliable choice for workwear blouses; tends to suit a classic British figure well.
Mango: Euro-fit, runs slightly small. Size up one if you're between sizes, especially for anything fitted.
Jigsaw: Beautiful quality and honest sizing. Tends to suit a slimmer frame, but their relaxed styles work for a wider range of bodies.
Anthropologie: Generous and often adjustable — many of their blouses have tie waists or elasticated details which help with fit. Great for avoiding the bust vs. waist problem.

Fabric: The Silent Sizing Factor

The fabric of a blouse changes how it fits just as much as the size label does. I once ordered two blouses in the same size from the same brand — one in silk, one in cotton poplin — and they fit completely differently. Here's what you need to know:

Silk and satin: Drapes with the body and is more forgiving. You can sometimes size down slightly for a sleeker silhouette.
Cotton and linen: No stretch, no forgiveness. Stick to your exact measurements — these fabrics will show every centimetre of misfit.
Chiffon and georgette: Floaty and drapey. Go true to size or even up — too small and it'll cling; the right size and it'll float beautifully.
Stretch-blend fabrics: The easiest option for tricky proportions. Size to your bust and the fabric adapts.

My Independent Brand Picks

I always try to call out some brilliant independent labels alongside the high street — because there's genuinely great stuff out there beyond the obvious. Right now I'm recommending:

Kitri: A London-based independent brand with beautiful structured blouses in cotton-silk blends. Their sizing is consistent, their fit notes on the website are excellent, and the quality punches well above the price point. A genuine discovery if you haven't tried them.
Sézane: French-owned and independent, with incredibly flattering blouses that have a relaxed Parisian ease to them. They run slightly small — size up one — but once you've found your size, the fit is genuinely beautiful. Their linen and cotton styles in particular are worth the investment.

Shopping Blouses Online: How to Avoid the Returns Nightmare

Always use the brand's own size guide, not a generic one — sizing varies too much for generic guides to be reliable
Read customer reviews specifically for fit comments. "Runs narrow in the shoulder" or "generous in the bust" from real shoppers is invaluable
Check whether the model's measurements are listed — if she's 5'10" and the sleeve looks slightly short on her, factor that into your decision
Look for brands that give actual chest measurements (in cm or inches) on the product page rather than just S/M/L
If you're between sizes, consider the cut: size up for structured styles, stay or go down for relaxed ones

One Final Stylist Note

If you find a blouse that fits your shoulders and bust beautifully but is slightly long in the body or loose at the waist — just buy it. A good local tailor can shorten a hem or take in a waist seam for very little money and you'll end up with something that feels completely made for you. The structural fit points — shoulders, armhole, sleeve length — are the difficult and expensive ones to fix. Everything else is straightforward alterations territory.

Never Guess Your Blouse Size Again — Use Tellar

Blouse sizing is genuinely one of the most inconsistent categories across fashion brands — which is exactly why I built Tellar, the UK's leading free sizing tool. Enter your measurements once — bust, waist, hip, or an existing brand size you trust — and Tellar instantly matches you to your correct size across 1,500+ brands. No more size guides, no more guesswork, no more returns.

Use the Store Size Lookup tool to get your precise size in any brand — whether that's Cos, Reiss, Whistles, Phase Eight or hundreds more. It works in-browser, it's completely free, and there's nothing to download.

And while you're there, explore the Tellar Fashion Hub — a growing library of free, honest, unbiased style guides written by real stylists. No ads, no sponsorship, no brand bias. Just genuinely useful fashion advice.

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Ella Blake is the founder and stylist behind Tellar — the UK's leading free consumer sizing platform, covering 1,500+ brands.