SUS online calculator

The System Usability Scale (SUS) is a widely used tool for measuring the usability and overall user satisfaction of a system or product. It was developed by John Brooke in 1986 and has since become one of the standards of testing.

It measures the perceived ease of use and usefulness of a product and provides a score that indicates its level of usability.

SUS Questionnaire

SUS Questionaire


Here are some interpretations of different SUS scores:

  • 0-25: Extremely poor usability. This indicates that the system is almost unusable and needs significant improvements to be useful to users.
  • 25-50: Poor usability. Users find the system difficult to use and would likely require extensive training or support to use it effectively.
  • 50-70: Average usability. The system is usable, but there are still significant areas for improvement that could lead to a better user experience.
  • 70-85: Good usability. Users find the system easy to use and navigate, with only minor areas for improvement.
  • 85-100: Excellent usability. The system is very user-friendly, and users find it easy to accomplish tasks with minimal effort.

About the SUS tool

The SUS Calculator allows you to quickly and easily calculate your SUS score based on your responses to 10 questions about the usability of a system or product. The SUS score is a single number that represents the overall usability of the system or product, with higher scores indicating better usability.

I want to acknowledge and give credit to John Brooke for his work on the development of the SUS, which has become an essential tool for measuring usability in the field of human-computer interaction.

To use the SUS Calculator, simply answer the 10 questions about the usability of the system or product, and click the submit button. Our calculator will then calculate your SUS score and display it on the page.

It’s worth noting that while SUS scores provide a general indication of system usability, they should be used in conjunction with other user feedback, such as qualitative feedback, task completion rates, and user error rates, to gain a more comprehensive understanding of the user experience.

Number of participants

The recommended number of participants for the System Usability Scale (SUS) tool is at least 5 participants. However, the more participants you have, the more reliable and accurate your results will be.

It is generally recommended to aim for at least 20 participants to achieve a statistically significant sample size. So each system being tested for can have 5 or 20 participants for evaluation, they could be increased to higher value when the time and resources permits

Please note that all responses are anonymous and will only be used to calculate the SUS score. The calculator does not collect any personal information.

Thank you for using the SUS Calculator and I hope it provides valuable insights into the usability of your system or product.

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