10 questions about online card sorting

6 min read David Renwick

Despite the abundance of user research methods, card sorting remains one of the best ways to get into the minds of your users and discover how they understand and categorize information.

Given that one of our most popular tools is an online card sorting tool called OptimalSort (You may have heard of it), we thought that we’d answer some common questions about online card sorting – the research method that OptimalSort uses.

Let’s begin!

1. What’s the difference between online and offline card sorting?

Traditional card sorting can be done using paper cards and hosted in-person, hence “offline”. Online card sorting is pretty much what it sounds like: a card sort hosted over the internet. But there’s a little more to it.

Primarily, running a card sort online as opposed to hosting one in person means that the process becomes much easier to facilitate. Instead of needing to schedule a time for your participants to come into an office, you can simply send them a link to your card sort. Then, they can complete the test in their own time.

Note that the very benefits of online card sorting mean that you can lose certain insights gained from an in-person card sort, like understanding why your participants sort cards in a certain way. There are ways around this, however. For example, you could pair your card sorting tool with an online video recording solution.

2. When should you run an online card sort?

Card sorting is best suited to answering specific, information-related questions. For example, maybe you want to rearrange the layout of your magazine? Or perhaps you need to add several new shopping categories to your website.

In the latter example, card sorting is the perfect technique to find out where people would commonly expect to find those categories on your website. In the card sort, you present participants with a list of cards containing the names of items within certain categories and task them with sorting those items into groups that make sense to them. The end result? You have a clear picture of how your users or customers would arrange the content on your website.

Card sorting is useful when you’ve got the information you need to organize, but you’re just not sure how to organize it.

3. Do I need to compensate participants for taking part in my card sort?

Compensation is tricky when it comes to online testing methods like card sorting. While there are no hard and fast rules, you may find that it’s the best way to incentivize people to take part in your study. Now, taking part in an online card sort is much easier than trekking across town to sit down for a user interview, so you may want to offer participants the chance to win a prize for taking part instead of compensating them directly.

Note: Offering a discount for your product or service is a great way to compensate users and encourage the use of your product. 

4. How do I make sense of the data?

Most card sorting tools offer powerful analysis functionality built right into the tool itself, so all you have to worry about is actually putting the card sort together, sending out the links and promoting it.

Using OptimalSort as an example, let’s take a look at some of the analysis functionality and why it’s useful. Other card sorting tools will likely have different analysis options available.

  • Participants Table: Review all of the people who took part in your card sort and segment or exclude them.
  • Participant-Centric Analysis (PCA): See the most popular grouping strategies as well as the alternatives among those people who disagreed with the first strategy.
  • Dendrograms: Quickly spot popular groups of cards and get a sense of how similar or different your participant’s card sorts were.

5. Is online card sorting expensive?

Online card sorting tools can be expensive, but it’s all relative. As just one example of this, online research platforms mean that you’ll likely be gaining access to a whole host of other tools by signing up for an online card sorting tool.

There’s also the fact that it’s a cheaper exercise overall than in-person card sorting as you won’t have to pay as much for compensation, or even use as much of your own time. Time is money!

6. Can I still get qualitative insights from an online card sort?

You can draw qualitative insights directly from the results of an online card sort, but you can also use online card sorting tools alongside participant recording software to build a more holistic understanding. By using recording software, you’ll be able to watch participants as they complete a card sort, and ask them to talk through what they’re doing to learn why they placed cards in a certain way. 

7. How many participants do I need?

In a nutshell, a larger number than you’d probably bring in for a user interview. Aim for between 20 and 30 participants.

Card sorting (whether it’s performed online or offline) is what’s known as a generative user testing method. This means that you’re typically starting without a design, and you’re using the method to get an idea of how people think with regards to the problem you’re trying to solve. A good example of this would be that you’re building a new website, and are using card sorting to learn how people think the content should be grouped and arranged.

Here’s a great quote from Nielsen Norman Group: “There is great variability in different people’s mental models and in the vocabulary they use to describe the same concepts. We must collect data from a fair number of users before we can achieve a stable picture of the users’ preferred structure and determine how to accommodate differences among users”.

8. How many cards should I use?

We recommend aiming for between 30 and 60 cards, as per our comprehensive 101 guide. Why? Because:

  • People will be more likely to complete your card sort.
  • You’ll only be able to include the most relevant cards, and be forced to discard the rest.
  • You’ll get enough useful data and insights to make informed decisions about your website, app or project.

9. What online card sorting tools are available?

There are a number of online card sorting tools available, including our very own OptimalSort, which is one of the tools included in our platform. OptimalSort has a number of useful features to make it easy to set up and run a card sort with participants based all over the world. Once you’ve gathered all of your responses, built-in analysis features can then help you make sense of the data.

Of course, there are other options available. Take a look at this tools map from User Interviews for a comprehensive overview of the major research tools.

10. What do I do after a card sort?

With your card sort done and dusted, it’s time to take that data and build a draft structure of your website or mobile app. Once you’ve put this rough structure together, you can use tree testing to to see how people navigate through it. We’ve got a guide for that too, which you can read here.


So that’s 10 questions about online card sorting – answered! If you’re interested in diving straight into a card sort of your own, we obviously recommend giving OptimalSort a try (which you can do for free).

Happy testing!