Fit Quiz for Shopify: Size Models

Learn about Size Models and using your unique size and fit settings in Fit Quiz

Updated over a week ago

"Size Models" is the fourth step in the integration process of Fit Quiz on Shopify stores. Size models are a unique feature of the Fit Quiz app on Shopify. They play a crucial role in recommending the correct size to shoppers. This article will explain what size models are, why Fit Quiz doesn't require size charts, and how to create a unique size and fit recommendation logic for your brand.

See the full step-by-step integration guide for Shopify shops here.

What are Size Models?

Size models are a special setting in Fit Quiz indicating whether selected items have a particular fitting to them. For example, an oversized item, or an item that is running slightly smaller. You can create as many or as few size models as you wish and use our default or your custom models.


The Fit Quiz algorithm uses these size models, along with your existing order and return data, to determine the unique style, size, and fitting factors of your items. This eliminates the need for size charts or garment measurements.

Want to learn more about our algorithm and how it recommends sizes? Check this article for more details.

Variables used in Size Models

Size models are set up in the Fit Quiz app using two variables: "Size and Fit" and "Sensitivity".

"Size and Fit" helps the algorithm understand the direction for the size recommendation. It indicates whether shoppers should go for a smaller, regular, or larger size and by how much.

"Sensitivity" tells the algorithm how sensitive the final recommendation should be to answers that customers give in the Fit Quiz widget. It is a reflection of whether the same size can fit a wide or a narrow range of shoppers. For example, oversized hoodies usually have lower sensitivity, while jeans – have higher sensitivity.

Preview/Demo of Size Models

Preview/demo of each size model is based on the model's "Size and Fit" and "Sensitivity" settings. This allows you to visualize how different types of customers, with varying preferences and body types, would receive size recommendations.

The demo showcases three different shopper personas:

  • Shopper A - This persona often struggles with items being too loose. They typically have a slimmer/narrower build and prefer tighter-fitted items

  • Shopper B - This is the average shopper with a standard build who doesn't usually struggle with sizing

  • Shopper C - This shopper often struggles with items being too tight. They tend to have a broader/wider build

Demo is available for each size model in the Fit Quiz Shopify app and can be opened by clicking the "View" link.

A demo is designed to indicate how the size recommendation will behave for different groups of shoppers described above. However, if you want to test Fit Quiz for every possible answer in the widget and see what size would be recommended, you would need to add Fit Quiz to your test theme and test this on a specific product.

Adding size charts or measurements

A common question among shops is where and how to add their size charts and measurements. The good news is that Fit Quiz doesn’t require any size charts or measurements, so there's no need to prepare or share these. Instead Fit Quiz uses your size models, which you can assign to products on the “Mapping” table and indicate their unique size and fit settings.

Using "Default Size Models"

Default Size Models are templates that Fit Quiz provides based on common sizing and fitting scenarios. They're designed to cover the most frequently used size and fit patterns based on our close work with hundreds of fashion brands globally.

These models include:

  • True to size – for products that generally fit as expected

  • One size up – for products that run smaller, customers should consider buying one size larger

  • One size down – for products that run larger, customers should consider buying one size smaller

  • Half size up – for products with a slightly smaller fit, suggesting customers buy half size larger

  • Half size down – for products with a slightly larger fit, suggesting customers buy half size smaller

These models are ready to use and can't be edited or deleted. To view a default size model, simply click on the "View" link to see the exact settings.

Creating "Custom Size Models"

In addition to default models, you can create Custom Size Models. These are perfect for products with special and unique sizing.

There's no limit to how many custom models you can create, and Fit Quiz can provide recommendations at the product level. This means each product or collection can have its unique size model if necessary.

To create a custom model, click the "Add custom models" button in the "Your size models" section.

You can name your model – ideally, choose a name that you and your team can clearly understand. Usually, shops select names based on:

  • fitting of items – for example, “oversized”, “slightly fitted”

  • collections – for example “winter drop” or “linen collection”

  • product categories or product groups – for example, “cargo pants” or “signature t-shirts”

Adjust the "Size and fit" and "Sensitivity" options using the slider. A demo on the right-hand side of the pop-up will show possible recommendations for different shoppers.

Remember, a size model is only used if it's assigned to a product. So, you don't need to use all the size models present.

Updating Size Models

If you're working with a new manufacturer or the sizing of your products has changed, you can easily modify or remove the size model. Please note that only custom models can be edited or deleted. Once you've made your changes, don't forget to click "Save".

Do I need to use all the size models displayed on the "Size Models" screen?

No, not at all! The "Size models" screen is merely a collection of all possible sizing and fitting settings. You can assign a size model to specific products on the "Mapping" screen. A size model is only utilized if it's associated with a product.

How many size models can I use?

You're free to use and create as many size models as you want. Fit Quiz can make recommendations at the product level, so if needed, you can even set up a unique size model for each product or collection. All our plans come with unlimited size models.

Need extra help?

If you require any additional help with setting up your size models, we will be happy to help.


→ What's next?

Congrats! You have just completed the fourth step of the Fit Quiz integration on your Shopify store. Time to move to the next steps:

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