SUS Definition

The System Usability Scale is a standardised questionnaire aimed at providing a 'quick and dirty' evaluation of a products usability

The System Usability Scale (SUS) is a standardised questionnaire aimed at giving a quantified score that represents the usability of a product or website. It’s a simple 10 question questionnaire with responses given on a Likert scale (strongly disagree –> strongly agree).

The SUS was was developed by John Brooke in 1986 to help measure the usability of electronic office systems.

The questions are as follows:

  1. I think that I would like to use this system frequently.
  2. I found the system unnecessarily complex.
  3. I thought the system was easy to use.
  4. I think that I would need the support of a technical person to be able to use this system.
  5. I found the various functions in this system were well integrated.
  6. I thought there was too much inconsistency in this system.
  7. I would imagine that most people would learn to use this system very quickly.
  8. I found the system very cumbersome to use.
  9. I felt very confident using the system.
  10. I needed to learn a lot of things before I could get going with this system.

Having used your product or website for a while, users are asked to complete the questionnaire. The scores are then computed, with the resulting score being 0 - 100, with higher scores representing a more usable product. Studies have shown the average score is 68, and anything under 50 is considered a concern.

It’s not without its limitations - but usability can be a hard thing to quantify, so the SUS can be useful in many situations.

Try it out

You can try the System Usability Scale Questionnaire on our interactive version - it’ll calculate a score once you’ve filled out the answers. If you want, direct your users to this page and get them to report the result.

You can read more about the System Usability Scale in this post.

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