Card Sorting
What Is Card Sorting?
Also known as: card sort, card sort study
Card sorting is a UX research method in which participants group labeled items into categories that make sense to them. Each item, a page, feature, topic, or piece of content, is written on a card, physical or digital, and participants organize those cards however they see fit.
The goal is to learn how users mentally model information, not how the design team has organized it internally.
What Are the Types of Card Sorting?
There are three main types, each suited to a different research question.
Open card sorting — participants create and name their own categories. This reveals how users naturally group and label content, making it most useful when building a new information architecture from scratch.
Closed card sorting — participants sort cards into predefined categories. This validates if an existing structure makes sense to users, rather than generating new structures from their input.
Hybrid card sorting — participants sort into predefined categories but can create new ones if needed. This works well when most of a structure is established, but gaps or unclear areas remain.
What Are the Benefits?
Direct access to mental models — instead of guessing how users think about content, card sorting surfaces that thinking directly from the people using the product.
Low barrier to run — sessions can be conducted remotely with digital tools, in person with physical cards, moderated or unmoderated, at relatively low cost.
Actionable output — results map onto navigation decisions and content groupings in a way that feeds directly into information architecture work.
Removes internal bias — categories that feel logical to the team often don't reflect how users think. Card sorts expose that gap before it gets built into the product.
What Are the Limitations?
Doesn't test findability — card sorting reveals how users group content, but not whether they can locate it once the structure is in place. Tree testing is better suited for that.
Participant volume matters — results from too few participants can suggest patterns that don't hold across a broader user base.
Label sensitivity — participants may group cards differently depending on how items are worded, so the quality of card labels directly shapes the quality of results.
When Is Card Sorting Most Useful?
Card sorting is most valuable early in a design or redesign process, when navigation structure and content groupings are still being defined. It also fits naturally into UX audit work, where existing structures are being evaluated, and teams need evidence from real users before committing to changes.