Every company needs to have a size chart - and actually, you need two.
The very first place to start in your product development is knowing the size range you want to produce. To do that, you need to think about what a "medium" size will look like within in your size range(s).
You can produce as many size ranges as you want to, but each range will need to have a "medium" and each of these "mediums" will need to be fit. If you haven't thought about arranging for fit models yet, this would be a great time to do that. Your garment sizes will only fit as well as they fit the size they are based on, so this initial block (or fitting shell) is REALLY important.
This might be redundant, but I'll chase it around anyway...if you are producing garments for petites, in small sizes, make sure your "medium" fits that description in every way. If you are looking for average sizes, and you are producing goods for North America, we can help you create sizing information that fits your demographic, and your company's look. See our post on Who is Your Ideal Customer? for more information on that. If you are designing for infants, the process for developing charts is different than described here. Contact us directly for information on that.
Your size charts should be unique to you. Don't copy another company's charts. You have a special look and style, and to some extent, there will be similarities, but take the time to develop your own.
A Size Range
I briefly mentioned above that you can do as many ranges as you want, but you need a "medium" fitting in every range. Now would be a good time, I think, to explain that, because in the process of making your charts, we will want to think about all the ranges you want to cover.
A size range is a maxium of 5 body sizes, which will be graded up and down from the "medium." Our company practice is to create ranges in maximum sets of 5 sizes, in order to refine the sizing, and therefore reduce waste. We also believe that this method produces a better customer experience.
Without getting into too many murky details about grading, keep in mind that you will want to set up your size charts with a grade rule in mind. Grade rules are the increments that your garment will grow or reduce between sizes. If you haven't given a lot of thought to that, it's ok. We can help you.
Actually, You Need Two ?
I need two? Yes, you do. Here's why. You don't want to show your customers (and your competitors) everything. And please, don't. After you have worked so hard taking measurements from your model, and going through the meticulous process of fitting, you will have one chart that has the full range of body specifications of your block pattern; and you will also have a basic, customer-facing chart with chest, waist, and hip measurements, and in some cases, length or age data.
Your internal full-body measurement specification chart is a secret document. If that were disclosed publicly, nothing would stop another company from duplicating your blocks, your styles, and or just basically taking an unfair shortcut by not having to go through all the effort and expense of fitting their own customers. I wish this was a world where such a thing didn't exist, but it does, so protect yourself. Don't show your full sizing information to anyone who doesn't need to see it.
In the beginning, all we typically show you is the customer-facing, basic size chart. This is because all the technical measurements are probably not necessary to help you picture your size ranges. But your can be sure that, as we are developing your charts, behind the scenes, we are connecting the chart to full specifications, and drafting your grade rules. We will use this information to draft your company's blocks, and later, grade the styles.
This, along with your initial fashion sketches, make up some of the first few pieces of your tech pack!
Congratulations on taking this first step! You are 1/3 of the way there!