Card sorting – tips and tricks

8 April 2015, Urszula Włodarska

How can one prepare a study that will help you organize the structure of a website/application? This article will provide you with all the answers to all the questions that you may have on how this method works. Stay with us to the very end!

What is card sorting?

Card sorting is a method of sorting cards that reveal how users classify content on a website, application or the Internet in general. The technique is based on a psychological theory that provides a mental model of how people conceptualize notions, patterns and how they categorize information. The ability to assign a given object to numerous categories and to introduce changes within them is distinctive to humans. Our brains have an amazing capacity to organize the necessary notions and connect them into the relational networks of neurons so that they are easily-accessible and “transparent”.

Similar ideas are utilized when conducting a card sorting study. Participants of the study organize topics, site navigation elements, subpage titles etc. into categories freely. As a result it is easier to find how the information architecture of a product should be build so that it is more accessible to users. The task of participants is to group the notions into structures which will be the best from their point of view. The next stage is searching for repeated patterns. With the use of these patterns it is possible to tailor the layout of subpages, labels and menu to the needs of users. To conduct a card sort test you can use actual cards where participants stick or write the labels, or you can choose the specific card-sorting software that is freely available on the market.

Which method should be used and when?

With a card sorting study we use the following methods that will depend on the complexity of the project and the needs of the client:

  • Open card sorting – participants receive specially prepared cards, sort them into groups and label them. This method is useful for the design of new sites and applicationsParticipants are asked to organize topics from website content into groups that make sense to them and then name each group they created in a way that they feel accurately describes the content. The open method helps to find out how users group and label categories for given content.


  • Closed card sorting or tree sorting – main categories are pre-defined and cannot be modified. This method is useful while adding content to the existing website.Participants are then asked to sort topics from website content into pre-defined categories. The closed card sort helps to find out how users sort content items into pre-imposed categories.


  • Free list sorting – participants create and name groups of cards and organize content within the categories they created themselves. This method is useful at the very early stages of designing a website structure.You can also find its variation, the so called “hybrid list”.
    The hybrid list is the combination of open and closed sorting. Participants to the study start with organizing website content into pre-defined categories (closed sort). However, if they find that the pre-defined categories are not suitable for their needs, they can create their own categories (open sort).

Conducting a card sorting study

According to the guru of usability Jakob Nielsen, the number of participants involved in the study should go from at least 5 to 15 which would be best since it means three times more participants. When the number of participants is increased, the number and importance of correlation increases.

The study can be conducted in two ways: individually or in a group. Individual card sorting is usually chosen for remote research when users are recruited and participate in the study online. It is also advised when the study requires involving a large number of participants. The whole process is overseen by the external company which provides the online tools (programs). The highlight to this study is that every user takes part in the card sort in their natural environment. This means that they feel comfortable and by means of that the study is not disrupted and its results are of higher quality. Moreover, we can now also follow the behavior and facial expressions of the participants so the results of the observation are also available.

In the case of traditional card sorting sessions, a larger number of participants is advised to foster creative thinking and enable drawing adequate conclusions. It’s difficult to analyze data on the basis of only one opinion. Moderators of the study facilitates a brainstorming session which leads to discussion where participants comment on their actions, ask questions and provide arguments. It confirms the idea of Donna Spencer who showed that group card sorting sessions provide more comprehensive information. For the requirements of such a session it is good to prepare the cards with categories beforehand and provide a large table that will facilitate a discussion. The downside to this approach is its superficial nature because participants are put in an experimental situation.

What’s the best number of cards?

It depends on who you’re gonna ask 🙂

For example Mark Boulton thinks that exactly 30 cards is enough. Specialists from think it’s within the range from 30 to 40 cards and according to them this is a lot, even for a open sorting study. At the same time card sorting specialist Donna Spencer describes in her book that the number of cards should fit within the range from 30 to 100.

As you can see there are different opinions here, but the most important part is to chose the website content that will really present its main goals. By means of that you will surely be able to prepare the right number of cards which most of the time doesn’t exceed 50. It is crucial to precede the card sorting study with another test that will show the areas to focus on.

How to analyze the results?

When using card sorting software the results analysis will be automatically generated. If the paper-pencil method was used you will need a bit more effort.

The results of a card sorting study can be presented in dendrograms if it was conducted with a larger group of respondents. Even though many specialists use this technique to analyze the results, not everyone opts for this method. According to Donna Spencer dendrograms can be difficult to interpret and illegible. This is why she advises that you enter your data into a ordinary spreadsheet application and take a look at these from every possible angle. If the study was conducted at a small sample it will be easy to find a general pattern.

card sorting eng

Cautions and advice

Some teams treat closed card sort as an evaluation for the existing categories of the website or the categories that are being designed in accordance to their idea. You need to remember that closed card sort is not a category validation method!

Just like during the design process we need to remember that the most important thing is to value the opinions on categories and site content that come directly from users. This is why some experts advise that you should provide the user with space and just observe their behavior, note their comments and try to see the categories from the user’s perspective.

If we impose categories to users we prompt them with a pre-built patterns in which they will try to fit even if they don’t necessarily see the situation in the same way. If users approach the content without any previous representations of categories in mind, they can really surprise us with their ideas.

Urszula Włodarska