Card Sorting: How to Uncover Mental Models & Inform UX Decisions

Card Sorting: How to Uncover Mental Models & Inform UX Decisions

Card sorting enables you to discover how people understand information, how they feel about different ideas, and helps designers structure the information of a site or product. Throughout this guide, we’ll explore the benefits of different kinds of card sorting, how to run a successful card sort, and which tools to use. Anchored in advice from UX design and research experts, stick with this guide to go from novice to pro in your card sorting skills.

Chapter 1

Card sorting: How to uncover mental models & inform UX decisions

Card sorting is a UX research method used to discover how people understand and categorize information. In a card sort, participants group ideas or information written on cards into different categories in a way that makes sense to them. You can use virtual cards, pieces of paper, or an online card sorting tool.

Researchers and designers most commonly use card sorting to:

  • Assess the information architecture (IA) of a website or homepage
  • Learn how people understand different concepts or ideas, and how they feel about them
  • Understand where users expect certain content to be found
  • Get inspiration for labeling and grouping content or ideas

Card sorting is such a valuable research tool, because it allows you to better understand people’s mental models and inform your information architecture, taking into account how the people who will use your product actually think.

Anca Croitoru, UX Researcher at New Relic

Try card sorting with Maze

Use Maze to run card sorting sessions and discover how users understand and categorize information.

In this first chapter of our Card Sorting Guide, we cover the benefits of card sorting, the different types and formats available to you, and some best practices to keep in mind before you get started.

TL;DR: How to perform card sorting

💡 Want to dive straight into how to conduct card sorting? Jump ahead to Chapter Two for a detailed walkthrough on conducting a UX card sort.

Before we dive into the benefits and types of card sorting, let’s have a quick rundown of how to conduct card sorts.

1. First, you need to pick the items you want users to organize—e.g. parts of your website or app—and write them on cards. These can be real cards for face-to-face sessions or digital ones for online card sorting.

2. Next, have participants sort the cards into groups that feel right to them. If it's an open card sort, they'll come up with their own group names. If it’s closed, they'll sort cards into pre-made categories of your choosing.

3. Finally, observe how participants group the cards you’ve provided for insights into their mental models. You can then use these insights to build information architecture that feels intuitive to users from the get-go.

So, that’s your whistlestop tour of conducting card sorts—but there’s plenty more to think about: you need to recruit the right participants, select the right card sorting method, and effectively analyze your results.

Luckily for you, we cover it all in this guide—starting with the fundamentals of card sorting and how it can help you build better UX.

The benefits of card sorting: Why you should conduct card sorting

Card sorting has many benefits within UX research and design, namely due to its ability to comprehensively understand a user’s way of thinking. It’s a powerful tool to grasp how users categorize information and determine the best way to organize and label the content on your website or product.

When working on information architecture, it’s important to match your users’ mental models, aka, the way they structure the content in their minds.

Guillermo Gineste, Senior Product Designer at Maze

Let’s get into more detail about a few of the main benefits of card sorting.

Find out what users think through mental models

A mental model refers to the explanation of someone’s thought process about how something should work and their expectations, based on past interactions with other products.

One of the main benefits of card sorting is that it allows you to make informed decisions based on users' expectations and mental models rather than based on assumptions.

Understanding your users’ mental models can then in turn inform a variety of decisions, including how to:

  • Sequence tasks in an activity
  • Structure databases
  • Organize navigational elements
  • Name features and interface elements
  • Group and provide settings

By using card sorting, you get to understand the user’s mental model or test if your existing mental model works as expected. Card sorting takes the guesswork out of it.

Guillermo Gineste, Senior Product Designer at Maze

Build a better website with improved information architecture

Information architecture (IA) is how you organize, structure, and label your content so that users can easily navigate your product and find the information they need. Creating an IA that's easy to understand and intuitive is key to providing a good user experience. That's where card sorting comes in.

Often, the way information is organized in a product subconsciously ends up reflecting the internal organization of the Product team. Card sorting allows designers to understand how users would perceive the product, and structure it accordingly.

Anca Croitoru, UX Researcher at New Relic

Card sorting is an excellent way to understand how your users expect the information architecture of a website or product to be structured. By presenting participants with different elements of the product and allowing them to group items into what feels natural, you’re able to get a deep level of insight into how potential users approach navigating your product and expect information to be structured.

These insights will allow you to make informed decisions and organize your content in a way that makes sense to your audience.

Empathize and connect with your users

Card sorting provides you with a glimpse into the perspective of your user. You can learn how people understand different concepts or ideas, and how they feel about them.

Whether it’s a selection of potential features or different naming conventions, card sorting is the ideal method to gain feedback from users based on their first impressions and instincts.

The best products are created with their user’s needs and pain-points in mind. Card sorting can allow you to start understanding these early on, before too much time has been invested in ideas that don’t align with your users.

Co-create names and categorization ideas with your users

Card sorting is an excellent way to gather new ideas from your target user base, from understanding naming conventions and colloquialisms to generating new categories or sub-groups.

By providing a group of potential users with the space and freedom to suggest ideas and categorize information in a way that makes sense to them, you are provided with a plethora of diverse thoughts and perspectives which are then yours to shape to your product.

Learn what works and gain insights quickly

Last but not least, card sorting is a simple and cost-effective method of quickly gaining insights about your users and how they think. Tests are easy to arrange and provide fast, reliable results.

As we explore in the next section of this guide, there are multiple ways to run a card sort—allowing you to easily connect with the users that will provide the most value for your research. You can run a card sort in person, using physical cards, or remotely using an online tool like Maze.

Get real, actionable card sorting insights

Maze's card sorts helps you learn how your users organize information and what resonates with them.

card sorting report

Types of card sorting: Open, closed, and hybrid

There are three main types of card sorting, and while each type serves the same broad purpose—understanding how your users interpret and categorize information—the different types do have their own ideal uses:

  • Open card sorting: for generating ideas and defining new information architecture
  • Closed card sorting: for evaluating current IA and naming conventions
  • Hybrid card sorting: for filling in gaps and flexibility

Determining the right type of card sorting for your research needs is a key part of ensuring you get the results you’re looking for and gathering high-quality, relevant data. When it comes to selecting the right type of card sorting, Vaida Pakulyte, UX Researcher and Designer at Electrolux, explains:

All card sorting types complement each other. Choosing the right type of card sorting comes down to the objective of your project.

Vaida Pakulyte, UX Researcher and Designer at Electrolux

Table showing differences between three card sorting types: open, closed, hybrid

Card sorting type comparison table

As well as your type of card sorting (open, closed, hybrid), depending on your objectives, you can then also choose from different card sorting formats:

  • Moderated vs. unmoderated card sorting: A researcher can conduct and oversee the session (moderated), or users work through the session on their own (unmoderated)
  • Paper vs. digital card sorting: You can either write the topics on physical index cards (paper) or type them onto cards in a simulated environment (digital)

Of course, as with any UX research, each method has its ideal circumstances, and its pros and cons. Let’s take a look.

💡 This section is supported by insights from Guillermo Gineste, Senior Product Designer at Maze.

Open card sorting

Open card sorting is a generative research exercise, rather than an evaluative one—meaning, it helps uncover and define the problem at hand, rather than evaluating a solution.

In this card sorting type, participants organize topics into categories that make sense to them and then create their own names for these categories.

The strength of an open card sort is in generating ideas and finding consensus amongst large numbers of people.

Guillermo Gineste, Senior Product Designer at Maze

This method helps reveal not only how users classify the cards but also what labels they use for each group, which generates new ideas and category names, and provides a deeper understanding of your user.

Vaida Pakulyte, UX Researcher and Designer at Electrolux, notes that “An open sort exercise is good at the beginning of the project because it helps you to understand how people naturally categorize information.”

If you're unsure how to organize your website or app information, an open card sort can help. The results from an open card sorting test are helpful in understanding how a target audience structures information, identifies potential bottlenecks, and can help to better label categories and sub-categories.

💡 Just how many users do you need to get the job done? For qualitative insights, 15-30 participants should do the trick. For quantitative data, you want to include 30+ participants. With your results ready and insights recorded, it’s time to take them to the team for reporting.

What is open card sorting good for?

In particular, open card sorts are commonly used to:

  • Create new information architectures or improve existing ones
  • Find patterns in how users expect to find content
  • Generate ideas for how to structure and label your website or app information architecture
Infographic showing pros and cons of open card sorting

Open card sorting pros and cons

Closed card sorting

Closed card sorting is an evaluative research method—it’s used to assess and validate potential ideas or solutions. In a closed card sorting session, you present participants with a pre-selected set of categories and ask them to prioritize and sort cards as it makes sense to them, within those defined categories.

This type of card sorting doesn't reveal how users naturally categorize a set of topics. Instead, it's usually used to test if existing category labels are clear. Guillermo suggests that: “Closed card sorting is ideal for testing existing information architecture, as you’ll only get the information you specifically need, so it’s really efficient.”

💡Did you know?

A dendrogram, aka tree diagram, is often the go-to for analyzing card sorting results. This visual helps you quickly see which topics are closely related (buddying up) and how they form larger categories (branching out). It's like getting a bird's eye view of how everything fits together, making your website’s flow easier to navigate.

What is closed card sorting good for?

Closed card sorting is a great way to test an existing structure, validate decisions when adding new items to an existing system, reorganize or rank content. You can use this method to:

  • Find out if users understand your categorizations
  • Pinpoint misleading categories and make informed decisions on how to improve
  • Ensure information is organized in a way that makes sense to your audience
  • Learn how users prioritize and rank information within existing categories
Infographic showing pros and cons of closed card sorting

Closed card sorting pros and cons

Pro tip ✨

You can also use a closed card sort as a follow-up to an open card sort to analyze if the categories identified in the first round seem logical to most users.

Hybrid card sorting

Hybrid card sorting is a type of card sorting that combines open and closed card sorting methods. Participants can group a set of cards into predefined categories, but they can also create new categories.

This technique is ideal for when you already have certain categories established, but you need input into how the remaining ones should be labeled, or aren’t positive on what goes where.

I use hybrid card sorting to map all the content of the website. First, I ask users and stakeholders to group the content into categories, and then I get the participants to name or create their own categories.

Vaida Pakulyte, UX Researcher and Designer at Electrolux

When improving a live website, the hybrid method might be most suitable. First, you can conduct a hybrid card sorting exercise to see how participants label and sort your website’s structure. You can then follow that up with a closed card sorting session that will help you validate the website’s structure and test if people can find the relevant information. Vaida explains: “Once the initial structure is set, then you can test it a second time with closed card sorting or a tree testing exercise.”

What is hybrid card sorting good for?

Hybrid card sorting is a great format if you’re looking to validate existing ideas and information, without closing off the potential for new ideas. It’s particularly useful if:

  • You want to test existing IA and website structures to see if they work as expected
  • You have some information categorized, but need input for organizing the remainder
  • The topic you’re researching is particularly complicated, as you can provide examples of categorization
Infographic showing pros and cons of hybrid card sorting

Hybrid card sorting pros and cons

Card sorting formats: Moderated, unmoderated, digital, and paper

Similarly to how you can choose from various types of card sorting depending on your objectives, you can also choose from different card sorting formats:

  • Moderated vs. unmoderated card sorting: A researcher conducts and oversees the session (moderated), or users work through the session on their own (unmoderated)
  • Paper vs. digital card sorting: Write the topics on physical index cards (paper) or type them onto cards in a simulated environment (digital)

Let’s take a closer look.

Moderated card sorting

Moderated card sorting involves a moderator who will debrief the participants and ask them follow-up questions following the card sort. This helps give you qualitative insights to understand the rationale behind the grouping.

Moderated card sorting is best for when you want quality over quantity. It may take longer, but you can gain deeper understanding by speaking directly with participants to learn their reasoning.

Guillermo Gineste, Senior Product Designer at Maze

Like all card sorting, moderated card sorts can be conducted with paper card sorting, or remotely using an online tool. However due to the nature of involving a facilitator, most commonly they’re conducted in person. Moderated card sorting often happens in the form of a one-to-one study, which allows the moderator to directly ask follow-up questions, or even ask the participant to express their thought process aloud while sorting.

When deciding the format of your card sorting study, determining between moderated or unmoderated is an important step. Moderated card sorting often lends itself to situations where you want to:

  • Gain a deep, nuanced understanding of the user, rather than a wide breadth of knowledge of a group
  • Understand the direct thought processes of users, rather than just the outcomes
Infographic showing pros and cons of moderated card sorting

Moderated card sorting pros and cons

Unmoderated card sorting

Unlike moderated card sorts, unmoderated card sorting requires participants to organize content into groups on their own, either as a solo activity or multiple users working together.

These sessions can be quicker and easier to organize as they don’t require facilitators, and you can use online card sorting tools such as Maze for conducting remote card sorting to collect insights.

I find unmoderated card sorting is best when you want to see results from a large number of users, for example how an existing IA works through closed card sorting, or you want to get as many ideas possible through open card sorting.

Guillermo Gineste, Senior Product Designer at Maze

Running your card sort as an unmoderated study gives participants the freedom and flexibility to do what feels right, without feeling as though they are being watched, which could make them reconsider their natural decisions.

Unmoderated card sorting is the format to go with if you’re looking to:

  • Get large amounts of feedback from multiple users, or multiple groups of users
  • Conduct a card sort within a limited budget
  • Uncover the most natural responses from users, and you don’t mind interpreting that data yourself (rather than speaking directly with participants)
Infographic showing pros and cons of unmoderated card sorting

Unmoderated card sorting pros and cons

Digital card sorting

In digital card sorting, you use online card sorting tools and card sorting software to simulate the card sorting drag-and-drop activity of dividing cards into groups.

This method is generally easier because it requires less resources, and the tool will do the heavy lifting of analyzing the card sorting results and revealing which items were most commonly grouped. It’s also much faster because you can get a sufficient amount of data in less time and identify patterns quicker.

Due to the availability of developed online tools, such as Maze's card sorting tool, digital card sorting can work well for open or closed card sorts, as well as moderated or unmoderated. When deciding between digital or paper/in-person card sorting, it often simply comes down to resource availability and location.

Digital card sorting works especially well if you are:

  • Looking to gain insight from a wide variety of participants, e.g. people from multiple countries
  • Under time constraints and need to conduct the card sort quickly and process results quickly
Infographic showing pros and cons of digital card sorting

Digital card sorting pros and cons

Try digital card sorting with Maze

Run digital card sorting sessions and discover how users understand and categorize information.

Paper card sorting

Paper or in-person card sorting is a more traditional technique, where you write down the topics on physical cards and ask participants to group them. This format naturally lends itself more towards moderated card sorting, but can also be conducted as unmoderated.

Guillermo Gineste, Senior Product Designer at Maze, suggests today there is little difference between digital and paper card sorting techniques. “The main advantage of in-person card sorts is that it allows for more complex groups (e.g. groupings within groupings). Apart from that, there aren’t many advantages versus using a digital tool; the data will look similar and you are able to ask the same questions.”

While paper card sorting is very flexible, with the availability of many intuitive and extensive online tools, it doesn’t offer much which cannot be accomplished through a digital card sort.

Ultimately, identifying the card sorting type that’s best for you comes down to the type of project you’re conducting, your user research goals, and available resources.

Infographic showing pros and cons of paper card sorting

Paper card sorting pros and cons

6 Card sorting best practices

Whether you're creating a new website or redesigning an existing one, following these best practices can help you make the most of your card sorting session and ensure reliable, actionable results.

1. Avoid creating too many cards

Matthieu Dixte, Product Researcher at Maze, finds having too many cards complicates the exercise and makes it take longer.

“It makes it harder for respondents to complete the exercise and drains their mental energy,” Matthieu says. “This could cause frustration, rushing the task, or even abandoning it—leading to poor results.”

If you have a large number of items to include in the card sort, consider what’s most important to start with—group similar cards and ideas into broader categories so your participants can concentrate on the most critical aspects of your website or application, leading to more meaningful and actionable results in the first instance. You can always run follow-up sessions later to delve into more detail.

2. Choose card names and order carefully

Just like the way you word research questions can impact your answers, the wording of cards can heavily influence a card sorting study. Ensure the wording on each card accurately represents the content it refers to, making it easy for participants to understand.

Matthieu shares an example where you’d want to understand how runners categorize their running shoes, so you create cards like minimalist shoes, trail shoes, racing flats, and stability shoes. “What if you conduct a closed card sort and ask them to sort these cards into two categories: ‘Good running shoes’ or ‘Bad running shoes’?”, says Matthieu. “You’re leading participants to categorize the running shoes based on perceived quality rather than actual use cases.”

In the same way you want to avoid leading questions when interviewing or surveying users, you want to avoid leading cards when conducting card sorting. Instead, use neutral instructions like “Please sort these cards into categories that make sense to you when thinking about different types of running activities.”

Pro tip ✨

Unless your target audience is familiar with specific industry terminology, you should avoid using jargon or technical terms.

3. Don’t mix child and parent categories

A well-structured and user-friendly information architecture can help participants understand the desired level of granularity in your card sorting exercise. For example, if you’re organizing content for a pet website, focus either on parent categories like ‘Dogs’ and ‘Cats’ or child categories like ‘Dog Breeds’ and ‘Cat Breeds.’

If you need to explore both levels of hierarchy, consider conducting separate card sorting sessions for each. This allows participants to focus on one level at a time and avoid any confusion.

Mixing child and parent categories during card sorting can cause misunderstandings regarding the relationships between the categories. The ambiguity of the hierarchy can increase cognitive load, taking people longer to answer and ultimately leading to inaccurate results.

Matthieu Dixte, Product Researcher at Maze

4. Choose your card sorting type carefully

“When deciding which card sorting type to use (open, closed, or hybrid), you have to consider what you want to learn from your study, the resources available, and the characteristics of your study panel,” says Matthieu.

For example, you could use an open card sorting session if you're designing a new online bookstore and want ideas for organizing virtual shelves according to customer interest. Participants could create their own categories, such as ‘Dark thrillers’ or ‘Cheesy romance’, giving you insights into their preferences.

On the other hand, if you're working on improving the navigation of an existing news website with predefined categories like ‘Politics’, ‘Sports’, ‘Entertainment’, and ‘Technology’, a hybrid card sorting approach might be more suitable.

In this case, you could feature existing categories while also allowing participants to suggest new categories or place cards in a ‘Miscellaneous’ or ‘I don't know’ bucket. This approach helps you validate and refine the current information architecture, as well as identify potential gaps and generate new ideas.

5. Randomize the order of cards

Let’s say you're conducting a card sorting exercise for a clothing website, and the cards represent different types of clothing items. Now, if your cards are presented to participants in a specific order—for example, first several T-shirts, then two smart shirts, then some blouses—participants may be more inclined to keep these items together.

That’s because the order they see the cards suggests that these items share a common category. While this may be true (they are all tops, for example), this is pushing a cognitive bias onto your participants.

Matthieu recommends consciously switching up how cards are given out, “Varying the order of the cards between participants will prevent any bias that the order of the cards might introduce.”

This approach helps ensure your card sorting results accurately reflect your users' mental models and preferences, leading to a more intuitive and user-centric information architecture. Matthieu also recommends pre-testing the card set with a small group of participants to double-check your instructions and chosen card sorting type work.

6. Recruit the right participants

When you set up your card sorting, you need to recruit research participants who actually represent the target users of your website or product. This includes getting a good mix of those who know your product well and those who might be seeing it for the first time.

Recruiting participants using UX research tools is great when you need lots of participants. Maze offers two solutions to help you locate and manage the right participants:

  • Quickly source and filter research participants with the Maze Panel based on your target demographic
  • Maze Reach allows you to automatically group and create a dynamic database of testers, based on traits and key metrics, to create segments and send email campaigns for future research
Reach - easy research participant management

Recruit the right users at the right time

Recruit from a diverse panel of over 280 million participants and collect high-quality responses to shape and speed up your decision-making.

When is card sorting right for you?

Card sorting offers several benefits as a user research method—here’s where you should consider card sorting:

  • When deciding how to group information on your website: Card sorting helps you understand how users naturally categorize and organize your content, allowing you to create an intuitive information architecture that aligns with their mental models. But using card sorting for highly technical or overly complex websites can be difficult for users without the relevant expertise to process.
  • The information already exists, you just need a structure: If you have a collection of content that needs organization, card sorting can help you determine the most logical and user-friendly structure for presenting that information on your website.
  • To improve UX and page navigation: While card sorting can help identify potential confusion in your existing navigation, you can also combine it with additional research methods like tree testing to evaluate how well users can navigate this new structure.
  • Understanding mental models: Card sorting reveals how your target audience perceives relationships between different pieces of content. This can help you design a website that resonates with your users' expectations and preferences.
  • Naming determined by your user: By observing how users label and describe various categories during the card sorting exercise, you can gain insights into their preferred terminology, ensuring your website uses language familiar to your audience.

Next up: How to conduct insightful card sorting

Card sorting is an excellent way to get ideas, gain feedback from users and understand how they think, gather insight on potential IA and discover your users’ mental models.

Whether you prefer to work with physical index cards or online card sorting software, with a moderator or not, every card sort will answer a different set of questions and provide new understanding of your users, so you can lay a better foundation for a user-centered design.

Now we’ve discussed what options you have when it comes to card sorting, let’s take a look at just how you can plan and execute a successful card sort within UX research.

Frequently asked questions about card sorting

What is card sorting used for in user research?

Card sorting (also called UX card sorting) is a UX research method that helps you discover how people understand and categorize information.

Is card sorting qualitative or quantitative?

Common goals when carrying out a card sorting study include: learning what users think about an existing IA, understanding why users group ideas in certain ways, and discovering how users categorize information.

These results could be qualitative, e.g. participant commentary during a moderated session, or they could be quantitative, e.g. statistics on time to complete the test, number of cards sorted, or percentage of cards in one group.

How long does a card sorting session take?

Generally, the time needed to complete a card sort will depend on several factors:

  • How many cards are used
  • How many users are participating, if working together
  • Whether the test is moderated
  • Whether you are collecting quantitative or qualitative data
  • Whether you are manually analyzing the data or have a tool to process this

Are there any disadvantages to card sorting?

As with all research methods, there are both advantages and disadvantages to card sorting. Some of the disadvantages include:

  • Unmoderated card sorting may not provide deep enough insights
  • Analyzing the results of a card sort (particularly a paper one) can be very time-consuming
  • Card sorting does not account for tasks at hand and wider context—for example, we may group tomatoes under ‘fruits’, however if the context was within a supermarket, they may be categorized under the ‘vegetable aisle’.

What are the main benefits of card sorting?

The main benefits of card sorting are that it enables researchers and designers to:

  • Discover users’ mental models
  • Empathize with users
  • Gain insights quickly
  • Gather new ideas
  • Improve information architecture