How To Extend Your Size Range For Existing Styles

When many brands first start out, they start small so they can test the market and build from there with more clarity and capital. Practically, this often means that size ranges start small at the beginning too. Many brands I’ve talked to want to become size-inclusive, but have had to limit their initial size range due to financial or logistic reasons in the meantime. The good news is you can always add more sizes once the brand grows. So, when that time comes, how do you go about adding new sizes? Today’s post goes over the how-to of extending the size range of your existing styles. 

Decide your new sizing

The first step in extending your size range is to decide what sizes you are going to add and what your new range will look like. It can be helpful to look at what other brands are doing. Make a list of other brands you like the fit of and research what their size ranges are. Be aware, though, that it is not always an apple-to-apple comparison between a labeled size from two brands. Make sure to look at the measurements on their size charts too. 

Plus sizes are particularly different between brands. Some brands offer a range of XS, S, M, L, XL, XXL, 3XL, etc. Others offer XS, S, M, L, XL, 2XL, 3XL, etc. A third may offer XS, S, M, L, XL, 1XL, 2XL, 3XL, etc., while a final may offer XS, S, M, L, XL, XXL, 1X, 2X, 3X, etc. Notice how the 3X is 3 sizes bigger than a L in the first example, while in the last example it is 5 sizes bigger. (If you’re curious, I like using the XS, S, M, L, XL, XXL, 1X, 2X, 3X, etc. range where the XXL and 1X somewhat overlap in bust measurement, but are different proportions. The XXL is still the same proportions of the missy size range with a smaller waist, while the 1X is more full proportions of the plus sizes with a larger waist compared to the bust measurement.) When you are adding new sizes to your size range, the first step is deciding what your range looks like and being clear about all the sizes you want to offer within the range.

Find a fit model

Fitting on a real person or multiple people is an incredibly important step of developing any new style and it is equally so when extending into a new size range. Find a fit model who is the middle size of your new range. She should represent the body size and shape of your average customer in that range. For example, if you started out offering XS-XL sizes and now want to offer 1X-5X as well, find a fit model who is a 2X or 3X to test out your new sizes. 

Even after you’ve extended the sizes of your existing designs, you’ll want to work with this same fit model on future styles in your new range. When you are making a wide range of sizes, it is best to fit two sizes/models during development. This will give you a better fit in every size and allow you to perfect the design’s proportions on multiple bodies. 

Grade up your existing pattern and save a copy

Now that you know what sizes you’re adding and who will be your fit model, it is time to start creating your new sizes with your patternmaker. When you don’t have any patterns in your new range to use as a block, you can start from the missy-sized pattern for the style. Save a copy of the pattern and grade the largest size of that pattern up to meet the measurements of your new extended fit size. You can look at your new size chart and see how much bigger the new fit size is from your largest previous size and add in that new amount to the pattern. At this point, the pattern is the right “size”, but it will probably not quite be the right shape for the new size’s proportions. That’s okay at this point – we’re just starting this process. 

Fit the new size

Now it is time to get the shape and proportions right in your new fit size. Cut a sample of the new pattern and fit it on your fit model. Work with your patternmaker or technical designer to pin and mark any changes needed in order to get a good fit for the size. 

Have a photo of someone wearing the original fit size of the style with you for this fitting. The goal is to make this new extended size range look the same as the original size range. The size is different, but the design details and seams should fall on the same parts of the body across all sizes. For example, if the original design was knee length with princess seams over the bust, you want it to still be knee-length in this new size and still have the princess seams centered over the bust. 

Make adjustments to the pattern

Having fit the new size on your fit model, your patternmaker will go back to the pattern and make the adjustments made during the fitting. This step seems obvious, but I mention it because your new adjusted pattern can now be used as a block for that new size. When you go to extend the sizes of other styles, you can refer back to the adjustments you made to this style and compare patterns. 

Depending on how close the styles are and whether they have the same or similar fabric, you can even use this new pattern as a starting point instead of sizing up from the other style’s pattern. Even if you can’t do that, making note of the changes you had to make to fit the proportions of this new size will help you size up the second style’s pattern. You’ll probably find you have to make some of the same adjustments. 

When your new fit size pattern is approved, your patternmaker can also grade that new base size into your remaining new sizes. This is where you’ll refer to the size range and measurements you gathered in the first step. 

Show off the new sizes

After you’ve extended your size chart and created the patterns for your new sizes, it is time to share your new sizes with your customers! When we are shopping, we all like seeing how a style will fit on someone similar to our size. Personally, I think extending your size range, but still only using one size of model on your ecommerce site or in your marketing is a wasted opportunity. You put in the hard work to extend your sizes and get the fit just right – why hide those new sizes and make it harder for customers in those sizes to shop? Showing models of different sizes wearing the same design along with details about their measurements and what size they are wearing in your brand will not only help your customers choose the right size to buy, but help them envision themselves in your designs!


Are you looking to extend your size range but aren’t sure what those new sizes should measure? My Graded Spec Chart Templates make it easy. You can make a whole graded spec chart to send to your patternmaker or factory (in either XXS-XXL or 1X-6X) with just a sample garment, tape measure, and 15 minutes of time – no math involved.

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