SUS Calculator
Answer the 10 System Usability Scale statements, or paste several participants, and get the score.
SUS measures how usable people think a product is. It does not show whether they completed tasks, or what to fix. Use it alongside task results and observation.
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Usability questionnaire
Participant: ______________________ Date: ______________
For each statement, circle the number that shows how much you agree. 1 = strongly disagree, 5 = strongly agree. There are no right or wrong answers.
| Statement | 1 | 2 | 3 | 4 | 5 |
|---|---|---|---|---|---|
| 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. | ◯ | ◯ | ◯ | ◯ | ◯ |
System Usability Scale, John Brooke, 1986. Printed from myuxacademy.com/tools/sus-calculator/
Where does your score sit?
80.3 and above
Excellent. Top 10% or so.
68 to 80.2
Good. At or above average.
51.7 to 67.9
Below average. Find out why.
Under 51.7
Poor. Expect real problems.
Writing the tasks for your sessions? Try the usability test script generator.
FAQ
How is a SUS score calculated?
Each of the 10 statements is answered from 1 (strongly disagree) to 5 (strongly agree). For the odd-numbered statements, which are worded positively, subtract 1 from the answer. For the even-numbered ones, which are worded negatively, subtract the answer from 5. Add the ten results and multiply by 2.5. That gives a score from 0 to 100. It is not a percentage, so 70 does not mean 70%.
What is a good SUS score?
The average across published studies is about 68, so anything above that is better than typical. Around 80 or higher puts you in the top 10 or so percent, and below about 52 is in the bottom 15 percent or so. The grades and percentiles here follow the Sauro and Lewis curve and are approximate. Compare against your own earlier scores and your competitors where you can, because that tells you more than a single number.
How many participants do I need for SUS?
You can calculate a score from one person, but it only tells you about that person. Scores vary a lot between people, so the average of five is a rough guide and the average of 12 or more is more trustworthy. Check the 95% interval the tool shows for several participants: a wide range means you need more people before you lean on the number.
Does SUS tell me what to fix?
No. SUS measures how usable people think a product is, not whether they completed the tasks or where they got stuck. Use it as a headline number next to task success, time on task and what you saw in the session. If the score is low, the sessions are where you find out why.
Can I change the wording of the statements?
Replacing "system" with "website", "app" or "product" is common and generally fine, and the tool lets you pick one. Changing anything else, or the order, can affect how comparable your score is, so keep the rest as it is. The questionnaire was published by John Brooke in 1986.
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