Double sizes—how does that work?

Dear users, dear designers,
with some patterns here on Crazypatterns, it says that double sizes are made, e.g. 36/38, 40/42, etc.
How should I understand the size range, or how big does it actually turn out?
Please tell me something about it. :- )

Hi Josefa,

I think everyone is familiar with the problem where you fit into a size 36 from brand XY, but even a size 38 doesn’t fit from brand YZ.
  That’s because every manufacturer can define its own clothing sizes. There’s no such thing as “size 36.” Size 36/38 is the size that would roughly fall in between. So, strictly speaking, it’s a bit loose for a 36 and a bit tight for a 38.

Italian clothing brands, by the way, tend to run quite small. So if you’re unlucky, you might even need a size 42 instead of a 36. (That actually happened to me with my wedding suit.)

Funnily enough, ready-to-wear sizes hardly differ in length. Go to a store and hold up the same top in size 38 and size 54 side by side. The difference in length is less than 10 cm.

  It works pretty much the same way with patterns. You just have to decide how to define the sizes. Of course, you could say, “Okay, I wear a size 36 or 38, or something like 36/38. That fits me now, so that’s the size I’ll use as a reference.” But then you’re limited to just one size.
  There are countless size charts online. They’re provided by companies that make sewing patterns or by clothing brands, etc.
Some of them list every measurement—from bust circumference to armhole to inseam.
You might want to stick to one chart and not use a different one for every pattern.

   With children’s sizes, it’s a bit different. There, the size is defined by height. So size 128 should theoretically fit a child who is 128 cm tall. The width, on the other hand, is based on the average measurements of children who wear that size.
Is your child 128 cm tall but, unfortunately, thinner than average? Well, that’s just bad luck. So you can decide whether your child should wear a crop top that fits in the width, or one that’s long enough but baggy.

You can probably tell by now. I’m not exactly a fan of ready-to-wear sizes. That’s exactly why I don’t use them.

If I’m going to make something myself and invest time and effort, it should at least fit—and fit right. 

If garments are very stretchy—like knitwear, for example—they can fit 2 or even 3 sizes.

I wear a size 40 in some clothes and a size 42 in others.
It’s best to check the measurements in the description and then compare them to your own.

When it comes to ready-to-wear sizes, I like to say, "every manufacturer rolls the dice differently."

Based on my size, I could be browsing the kids’ section, while my measurements belong in the women’s section.

That’s one of the reasons why I make sweaters and skirts in a way that allows for individual adjustments.