Why Plus Size Clothing Sizes Make No Sense (And How to Finally Find Your Perfect Fit)

Have you ever tried on a size 20 in one brand, a 22 in another, and an XL somewhere else—all on the same shopping trip?

You're not imagining it. For many, buying plus size clothing feels like a guessing game. One brand's size 18 fits perfectly, another requires a size 22, and a third doesn't even use numbers at all.

The truth is, there is no universal plus size sizing system. Instead, there are multiple sizing approaches used around the world, each with its own measurements, grading rules and fit philosophy. Add in differences between countries and individual brands, and it's no wonder finding clothes that fit can feel frustrating.

The Five Languages of Plus Size Fashion

One of the biggest reasons plus size shopping is so confusing is that brands don't all speak the same sizing language.

1. Numeric sizing

This is the system many Australian and UK brands use. For example:

• 16
• 18
• 20
• 22
• 24
• 26
• 28
• 30
  

While it appears straightforward, there is no rule that says every brand's size 22 must have the same measurements. One brand's size 22 may have a 122 cm bust, while another may measure 128 cm. This is because each brand will use its own set of increments and grading rules to increase the size. In major fashion brands this sizing system usually reflects grading up into plus-sizes from a size 10 block. No wonder so many plus sizes often just don't fit right.

2. Letter sizing

Many brands use:

• XL
• XXL
• XXXL
• 4XL
• 5XL
• 6XL

There is no universal definition of what an XXL actually means. One retailer may consider XXL equivalent to an Australian size 18, while another may use it for a size 22.

3. X sizing

Particularly common in North America, you'll often see:

• 1X
• 2X
• 3X
• 4X

A common misconception is that 2X simply means XXL. It doesn't. In many brands, XXL and 2X are completely different sizes with different body proportions. This X sizing system usually reflects using plus size blocks, to design, often a size 18-20, but not always.

4. Brand sizing

Some labels create their own simplified sizing systems. For example:

• Size 1
• Size 2
• Size 3
• Size 4
• Size 5

Without checking the brand's size guide, these numbers tell you almost nothing about the garments actual measurements. And if detailed garment measurements aren't supplied, the system is no better than any other. 

5. The 'W' Measurement

Just when you think you've figured out plus sizing, another system appears. Some brands and retailers use a W designation, such as 18W, 20W or 22W. 

The "W" generally stands for Women's, but it doesn't simply mean a standard size with an added letter. In many cases, garments labelled with a W are drafted with different body proportions, such as a fuller bust, waist, hips or upper arms, rather than simply being larger versions of straight-size clothing. 

To make things even more confusing, not every brand uses the W system in the same way. Some retailers use it extensively, while others don't use it at all. So a customer shopping internationally might find themselves choosing between:

• Numeric sizing (16–30)
• Letter sizing (XL–6XL)
• X sizing (1X–6X)
• Brand sizing (1–6)
• W sizing (18W, 20W, 22W)

Five different systems—and still no universal standard.

Then every brand creates its own rules

Even if every brand used the same sizing system, shopping would still be difficult.

That's because every brand decides:

• where measurements begin
• how much each size increases
• whether garments are designed for a fitted, classic or oversized silhouette
• how much ease is built into each style
• which body shape they design around

This process is known as grading. There is no universal grading standard for plus size clothing. Some brands increase each size by 4 cm through the bust and others increase by 6 cm. Some change sleeve width dramatically and others barely adjust it at all. This means two garments labelled exactly the same size can fit completely differently.

Shopping in different countries is even more confusing

International shopping adds another layer of complexity. A customer might wear: 

• Australian size 22
• UK size 22
• US size 18
• European size 50

Meanwhile another retailer may use only XL sizing. Another may use 2X. Another may use Size 4. All of these may fit the same person—or they may not.

Why this matters even more for plus size bodies

Straight-size clothing is often designed around relatively small measurement changes between sizes. Plus size bodies are far more diverse. Two people who both wear a size 22 may have completely different proportions. One may carry more weight through the hips. Another through the bust. Another through the waist. Another through the upper arms. This is why relying on a size label alone rarely produces consistent results.

The best way to shop isn't by size

The single most reliable way to buy clothing online is to know your body measurements. A soft measuring tape tells you far more than a clothing label ever will. Knowing your key measurements allows you to compare against each brand's size guide rather than guessing whether you're usually an 18, a 20 or a 22. It takes just a few minutes but can save countless disappointing purchases. 

The challenge isn't just inconsistent sizing. Many brands also provide limited measurement information, making it difficult to compare garments across different labels. Knowing your body measurements is only half the equation—you also need accurate garment measurements to understand how a piece is designed to fit.

At Gertrude & Loom, we're taking a different approach

We don't believe you should have to decode four different sizing systems just to buy beautifully made clothing. We're building our fit process around real plus size bodies, detailed garment measurements and honest fit guidance. When our range drops and our online store fully opens, we will ask you to take the following measurements, and we'll provide instructions on how to do it.

• Height
• Bust
• Empire circumference
• Shoulder to empire line length
• Waist
• Seated waist
• Hips
• Upper arm circumference
• Thigh circumference
• Calf circumference
• Crotch length / body rise

You'll only need to do this once and keep the measurement. With these measurements you'll unlock the secrets to knowing whether the garment is a fit for you before you buy. Our goal isn't simply to tell you what size to buy. Our goal is to help you find clothing that genuinely fits your body. 

Final thoughts

If you've ever wondered why you seem to wear a different size in every brand, the answer is simple: You're not changing. The sizing system is. Until the fashion industry adopts a consistent standard, the best tools you have are accurate body measurements, detailed garment information and brands that are transparent about how their clothing fits. That's exactly the future we're working towards at Gertrude & Loom—one beautifully fitting piece at a time.

Gertrude & Loom is launching soon. Sign up to our newsletter below to get early access and launch offers when our collection of plus-size garments, in natural fibres drops later in 2026.  Click the social tiles below to follow us.