System Usability Scale (SUS)
A ten-statement questionnaire answered right after using a product, giving a 0 to 100 score for how easy it was to use.
What it’s for
It helps you put a number on ease of use, which observing a test doesn’t give, to compare versions or products quickly.
Key elements
Ten statements, five answers
Each statement is rated from “strongly disagree” to “strongly agree.”
Positive and negative, alternating
That way people read each statement instead of ticking everything the same.
A score, not a percentage
The 0 to 100 is for comparing; a 70 doesn't mean 70%.
How it’s done
The person uses the product or does the test tasks.
They answer the ten statements, without overthinking them.
Calculate the score and compare it with other versions.
Applications in design
When to use it
At the end of a usability test, or to compare two versions of the same product.
Avoid
Reading each statement on its own, or taking the number as a diagnosis of what fails.
Don’t fall for it
Always pair it with what you observed in the test, which explains the why behind the number.
Connections
Related to
Authors and works
- 1996
John Brooke
Created the scale in 1986 at Digital Equipment Corporation and made it free to use; he published it in 1996 as a “quick and dirty” measure of usability.
- 2013
John Brooke
Reviewed nearly three decades of use and clarified that the score isn't a percentage and should be read by comparing it with others.
Sources
Original sources
- Brooke, J. (1996). SUS: A “quick and dirty” usability scale. In P. W. Jordan, B. Thomas, B. A. Weerdmeester e I. L. McClelland (Eds.), Usability evaluation in industry (pp. 189–194). Taylor & Francis.
Academic reviews
- Brooke, J. (2013). SUS: A retrospective. Journal of Usability Studies, 8(2). View source: Brooke, J. (2013)
Last reviewed: