
Nearly half of shoppers in the U.S. buy multiple sizes of the same apparel item with the intent of returning the ones that don’t fit. That’s according to a survey that was conducted in the summer of 2019, before the pandemic. With the resultant surge in and broadening of online shopping since then, we can infer this practice has only increased. Which means more brands may be seeing narrower profit margins.
Providing more comprehensive and intuitive sizing information to increase conversions and decrease returns – seems like it should be a simple win, right? The surprising thing is how many online retailers don’t do it. In fact, research from the eCommerce UX experts at Baymard Institute shows that 43% of the benchmark sites Baymard looked at either failed to provide any sizing information or didn’t provide sizing information that was usable.
What are the repercussions? In addition to losing short-term revenue and incurring extra costs, the hassle and frustration of buying the wrong size can also lead to longer-term losses, such as lower customer lifetime value (CLTV) due to bad customer experience.
Best practices for providing sizing information
Although there are some innovative tools to help customers with sizing and fit (we’ll get to those later in this post), at the very least, brands need to make sure that customers can easily understand the sizing and/or fit information. Don’t make customers do the math or guess which section of a body part they’re supposed to measure.
Women’s retail is particularly fraught with sizing challenges, due to an overall lack of standardization. In addition, for non-apparel products like furniture and appliances, it can often be difficult for customers to determine if a product will fit in a particular space.
Providing irrelevant sizing information can be as harmful to the user experience as providing inadequate sizing information. Baymard Institute testing shows that when customers get a generic sizing chart and have to scroll through it to find information relevant to the product they’re shopping for, they often give up. Users also reported that receiving irrelevant sizing information damaged their perception of the product and site.
According to Baymard research and based on our experience designing eCommerce sites, some key best practices to follow for sizing include:
- Findable: Providing sizing information where customers can intuitively find it; e.g., near where customer will select their size to purchase
- Intuitive: Ensuring that sizing information can be easily understood
- Clear: Providing international size conversions, including the different numeric sizes by region (e.g., Europe, U.S.), and measurements in inches and centimeters
- Relevant: Providing sizing information specific to the product you’re selling; i.e., don’t provide sizing information for shirts if the product is a pair of gloves
- Helpful: Providing guidance on how to take measurements to determine size and fit
Be obvious
Don’t make customers hunt for the size guide. Sizing information should be located on the product detail page (PDP), near where the customer selects size. Many brands provide a link to a pop-up sizing chart; another simple solution is to add the sizing chart as one of the product photos in the image gallery.
For products like furniture and appliances, include product dimensions on the PDP! Don’t require customers to download and read the product manual.
Finally, if sizing or fit are often purchase barriers for certain products, consider providing an easy link to or information for contacting customer service on the PDP.

Add more details or instructions
Why stop at a sizing conversion chart? Some retailers have added extra information that can help customers determine fit. For example, Patagonia labels its styles in fit categories (i.e., Formfitting, Slim Fit, Regular Fit, Relaxed Fit) and includes a fit guide that shows illustrations of how the fit is different between these categories. The brand also provides clear instruction on where/how to measure relevant body parts.

Additional instruction can also be essential for non-apparel brands -- for example, a brand selling furniture. Joybird includes details on how to measure the different areas of a home (e.g., hallways, stairs) to ensure that a piece of furniture will be able to be moved from the delivery truck into its new spot.

Carpet seller Flor is another example of how a little extra information can go a long way. To help customers determine how many carpet tiles they’ll need for a space, Flor provides some useful diagrams for typical room situations.

Model which size
Including information about what size the model in the photo is wearing can be very helpful as a point of reference to help customers understand how the item might fit on them. A great place to put this information is as a caption on the photo in the image gallery.

Non-apparel brands can also “model” the fit of their products. Furniture brand Interior Design gets creative by showing how models of different heights “fit” on a couch using simple videos of people sitting on it.

Compare and contrast
An intuitive and visual way to help customers decide between different fits and styles is with a comparison chart. For example, Luluemon provides a side-by-side look at its leggings, highlighting differences like activity, fabric and length options.

Madewell’s comparison chart takes it up a notch with really great UX. Users can click on three different sizes on the left and instantly see how each jean style will look on that body type. Also, some of the stills of the models are actually video, so customers can really see how the jeans fit and move.

Try it on
Depending on the product, you may be able to help your customers “try it,” either physically or virtually. For example, Pit Viper provides clever paper cut-outs of its sunglasses to help customers compare the different models by holding them to their faces.

In addition, augmented reality (AR) tools (Shopify supports AR) can enable customers to place products on an image of the customer’s body or face, or in a room setting using a mobile app. Solstice Sunglasses allows customers to “try on” sunglasses from its website using a devices’ camera, Warby Parker has an app for “trying on” glasses, and Ikea and Wayfair have apps that help customers visualize if furniture will fit in a space.

Leverage customer reviews
Some review apps, such as Yotpo, include fields to prompt customers to indicate their height and weight, and if a product was small, true to fit, or large, which can be very valuable information for other customers. Asking for this feedback in reviews can also help address sizing issues that are due to factors like fabric type – e.g., a stretchy fabric might necessitate ordering a size down from a customer’s normal size.
Get technical
Technology tools exist to help with fit. One is True Fit, a platform trying to address apparel’s non-standard sizing problem. Using AI, data points from major brands and retailers, and customer responses to a few questions about preferred fit and styles, True Fit provides a brand’s customers with a selection of product recommendations to browse.
Conclusion
Sizing information is a vital piece of the eCommerce customer experience that often doesn’t get the attention it deserves. Clear and useful sizing information builds trust with customers, who feel confident to come back and purchase again. In addition to building customer long-term value, using best practices when it comes to structuring and displaying sizing information also will help you reduce returns, which could be a huge win for your bottom line.