How to Choose Your Product’s Size Range. Numeric Sizes vs Letter Sizes

Choosing an appropriate size range for your apparel products will usually have more impact on your branding than what you might think, especially if FIT is high on your list of priorities for brand identity. The available sizes you decide to offer can send a message to whom you see as your target customer and what market you are going after.

When it comes to apparel there are two standard size ranges:

  • Numeric – US women’s wear usually uses 0,2,4,6, etc. The European equivalence is more directly related to actual measurements and size numbers 30,32,34,36…and so on. Other countries around the world have their own numeric sizes.
  • Letters – XS, S,M, L, XL etc. these are more universal

Many consumers as well as young designers assume that choosing one of the above sizing standards is just a simple preference made by the brand, but in fact there is an important reason behind the decision. The fundamental difference between these two standards is in the GRADING. 

**Grading is how much a pattern increases or decreases between sizes.

General standard grading for Numeric Sizes:

  • Size 00-10: 1” all around circumference (e.g.: Between a size 2 and 4, the bust, waist, and hips measurements will each increase 1” in circumference)
  • Size 10 and up: 1.5” all around circumference between sizes

General standard grading for Letter Sizes:

  • Size P – L: 2” all around circumference between sizes
  • Size L and up: 3” all around circumference between sizes

Letter sizes are usually meant to cover a wide range of sizes, for example: 

XS = 0-2 , S = 4-6 , M = 8-10 , L = 10-12

To decide which method will work best for your product consider the following:

  • Style and fit – T-shirts, sweatshirts, hoodies, pajamas or even overcoats etc. usually have a looser, more relaxing fit which is why the majority of these styles have letter sizes.  Fitted dress pants, a fitted button down shirt or dresses have more importance placed on fit and therefore you want less grading differences between sizes.
  • Fabric – Depending on the amount of stretch, styles made in a stretch fabric, such as active or performance wear, you might choose to run letter sizes. The same might go for really heavy fabrics such as a coat fabric where 1” grading might not make as much of a difference.
  • Look – Letter sizing is often most appropriate for and best fits the definition of casual wear, whereas dressier and formal wear that uses number sizing is often perceived as higher end due to its higher fit standards and quality.
  • Market and branding choices – How do you want your product/brand to be perceived? If your product promises better fit, higher end quality and price point, choosing number sizes would be the best option. This also ties back to price point; letter sizes allow you cover more ground with fewer sizes. For example if we look at the above chart again we can see that to cover the size range of 0 to 12 using number sizes will require 8 different sizes while using XS-L will only requires 4 sizes hence, cheaper and easier for production.

Before you make a decision do your research by studying your market and competition. Learn about size range and grading rules, consider the specific product,  know your target customer and how they will wear this style. Although there are some standards for sizes and grading rules, ultimately each brand can adjust those to fit their strategy, target customer and market. This is the reason why we find ourselves fitting in different sizes in different brands. And we all heard about vanity sizing, right?