UX Research How Many Users Do You Need For Usability Testing

UX Research; How Many Users Do You Need For Usability Testing?

6 minutes read

It is quite common when UX researchers to feel that usability testing is to be reserved for only rare design and product development projects. This mainly stems from the belief that usability studies require a large pool of users which will increase the budget for the project, take a ton of time, and a prolonged period of analysis. While usability tests could be complex depending on what your project is about, it doesn’t always have to be expensive, especially not because of the number of users you need to run your test. In general, bringing a lot of users on board will only waste your time and money. According to the Nielsen Norman Group, the golden number for usability test participants is 5. And that’s it. But there is a catch; it isn’t always that simple.

In this article, we explore how to choose the number of users to use in your usability test for the best results, save resources, and move your project forward. 

How Many Users Do You Need For Usability Testing?

How Many Users Do You Need For Usability Testing

For usability testing, you’ll need at least 5 users. That’s the magic number. Usability testing with as few as five participants reveals about 85% of problems. According to research by the Nielsen Norman Group, after testing a fifth user, you begin to gain no new information, almost all of your new insights would have been revealed by the 5 users. And you won’t learn very much new information.

Here is how usability tests typically go. The first user will offer the most insights on usability. The second will repeat much of what was observed by the first, but with additional insight. The third will produce a lesser amount of fresh insights than the second, and so on. By the time you test a sixth user, most of what you’ll hear from them will be repetition. 

Usability testing with only 5-7 respondents can provide valuable insights for rolling out new features on a site, assessing specific activities, or conducting basic UX research. However, no-shows, technical difficulties, and quiet participants might derail your testing. In the event that any of them don’t show up, you may recruit a few extra individuals and use a thorough screening process. 

5 Users is Cost Efficient

For a company, testing five people in one day is both cost-effective and practical.

Because they’ll be familiar with your product, company, and role, colleagues, family, and friends are not ideal candidates for usability testing. This might cause prejudice. User recruitment firms may find participants for usability tests that aren’t affiliated with your firm.

A usability test in Dublin, like those found in other European tech cities, may cost around £100 per user and include a bonus of $50 per user employed by a recruitment firm. The average agency charge in the US is $107, whereas it costs anything from £100 to £120 per person in the United Kingdom. This doesn’t account for other related expenses such as equipment and software. It is recommended to always record your sessions. With the rise in remote usability testing, you can depend on tl;dv for all your research recording, notetaking, and transcriptions.

For a full day, usability testing may cost upwards of 900 Euros, dollars, or pounds. Testing can reveal critical user concerns and insights that you couldn’t otherwise discover. It’s also an excellent investment since it helps you identify important user issues and observations. With just five participants, you can conduct a whole round of user testing in one day. When you want to go with more than 5, that means more days and more resources spent on your usability testing. 

To make the most of your working day, set aside an hour time block for each user with at least a thirty-minute break between sessions. You may use that time to collect your thoughts and make notes on the previous session.

Five Users Are Enough to Get Quality Insights

Why is it that five people is the ideal number for testing? After three or four users, most usability issues tend to repeat themselves. The first three users are extremely likely to encounter nearly all of the major challenges, and it’s critical to do more rounds of testing rather than squeeze everything you can out of each round.

While he’s correct in that major difficulties will recur, people frequently drop out of usability testing. If you’re left with two participants, it’ll be tough to get the information you need. You require additional protection than three users do.

When the 5 Users Rule Breaks Down

There are a few exceptions to the five-user rule that should be noted. If you’re testing a website or app with a lot of features, remember to test five users for each function.

Consider testing the purchase and check-in processes of an airline website. Rather than attempting to cover both features in one test, it’s better to distribute them across two separate tests. Here, ten people are suggested; five should be allocated to the purchase process and five to the check-in procedure.

When stakeholders demand statistical evidence from usability testing, the rule of five may have to be violated. While this isn’t an ideal approach in a qualitative study, it is sometimes unavoidable.

A senior manager may request quantitative proof that the company’s registration and login are ineffective, claiming that they don’t believe them to be. To demonstrate that 12 out of 20 users had difficulty generating a password or 17 out of 20 users had difficulty logging in, you might have to test 20 users.

Ideally, seek to persuade stakeholders not to embark down this road ahead of time! Whenever feasible, aim for a minimum of five users. In the long run, it’s more beneficial for your user experience and the company’s overall goals.


All in all, it’s not always necessary to bring on a boatload of users for your next usability test. You can actually get good insights with just a handful of participants if you have the right test setup and are ready to analyze and synthesize your data properly. And if you don’t want to go through all that hassle, we at Try tl;dv have got your back. Our platform is designed to help you quickly record all your research tests so you can make informed design decisions without breaking the bank or wasting time. So what are you waiting for? Start testing today!