System Usability Scale (SUS) | Usability.gov

If you are considering using a SUS, keep the following in mind:

• The scoring system is somewhat complex
• There is a temptation, when you look at the scores, since they are on a scale of 0-100, to interpret them as percentages, they are not
• The best way to interpret your results involves “normalizing” the scores to produce a percentile ranking
• SUS is not diagnostic - its use is in classifying the ease of use of the site, application or environment being tested

When a SUS is used, participants are asked to score the following 10 items with one of five responses that range from Strongly Agree to Strongly disagree:

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.

The questionnaire and scoring are outlined in the System Usability Scale (SUS) Template .

Interpreting scoring can be complex. The participant’s scores for each question are converted to a new number, added together and then multiplied by 2.5 to convert the original scores of 0-40 to 0-100. Though the scores are 0-100, these are not percentages and should be considered only in terms of their percentile ranking.

Based on research, a SUS score above a 68 would be considered above average and anything below 68 is below average, however the best way to interpret your results involves “normalizing” the scores to produce a percentile ranking.