As soon as you collect intel from a single test user, your insights shoot up and you have already learned almost a third of all there is to know about the usability.

When you test the second user, you will discover that this person does some of the same things.

Each new user adds a bit more insight than the last, but you will keep seeing the same things again and again. Thus, learning less and less new insights each added video.

We recommend 3 users for our budget customers.
Three users is enough to get an idea of the diversity in user behavior and insight into what’s unique and what can be generalized.

We recommend 5 users for most people.
Five is the best return on investment. Testing costs increase with each additional user, yet the number of findings quickly reaches the point of diminishing returns. Have a bigger budget? YAY! Spend it on more tests, not more users in each test.

We recommend 9 users when you are looking for as much feedback as possible.
You would need at least 15 users to catch 100% of the usability errors. This is overkill for most businesses. It’s better to run a larger quantity of smaller tests. 🙂