System Usability Scale – The Universal Marker of Product Usability
System Usability Scale, or SUS, provides a single score on a scale of 0–100, so it can be used even for systems that are quite different from one another.
Because it allows for comparisons on a relative rather than an absolute basis, it allows for UX professionals to quickly run a range of tests of different assets, or the same asset over a period of time, and compare the SUS score.
How Does It Work?
Participants are asked in a survey questionnaire to indicate their level of agreement or disagreement with a number of statements in relation to systems, websites, apps, or prototypes (“Please indicate how much you agree or disagree”).
Userlytics’ SUS activity is preformatted and automatically calculated. The questions are ordered in an alternating “positively framed’ and “negatively framed” manner, with slightly different wording that is related to the usability and user experience that the participant perceived. This makes it easy for you to add a SUS task to your study, and begin gathering key data.
How do I Interpret System Usability Scale Scores?
Interpreting the scores usually involves the following process: 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. These are not percentages and should be used in terms of their percentile ranking.
A SUS score above a 68 is normally considered above average and anything else below average, however, it is best to use the score to compare different iterations of a design, and/or compare against a production asset, and/or compare against a competitor asset or a “best practice” asset.
Benefits of the System Usability Scale
Industry standard
measurement
Because the System Usability Scale has become an industry standard, with references in over 1300 articles and publications, it provides a clear “standard” benefit in terms of comparisons.
Quick and simple
set-up
The Userlytics system calculates the system usability scale (SUS) score automatically, and presents MIN, MAX AND AVERAGE results. All you need to do is fill in the blanks!
Reliable results
and analysis
When used with small sample sets, SUS is historically shown to be a very reliable measurement of product usability and likeability, making it an ideal UX testing tool.
Effective UX
testing tool
The System Usability Scale is also historically shown to be quite effective in differentiating between different study assets, and between good and bad digital product usability and likeability.
FAQs
What does the System Usability Scale (SUS) measure?
The System Usability Scale measures the usability of systems, websites, applications, and prototypes. It evaluates user experience based on survey responses and provides a single usability score on a scale of 0–100. This score helps UX professionals compare usability across different iterations, designs, and competitor products.
How do you measure system usability using the System Usability Scale?
To measure system usability with SUS, participants answer a 10-question survey designed to assess their level of agreement or disagreement with usability statements. Questions alternate between positive and negative framing. The scores are calculated to generate an overall usability score.
How is the System Usability Scale calculated?
SUS scores are calculated by converting participant responses to a numerical format, summing the adjusted scores, and multiplying by 2.5 to scale results from 0–100. It’s important to note that these scores represent a percentile ranking, not a percentage.
Is the System Usability Scale still relevant?
Yes, the System Usability Scale remains highly relevant as a reliable and standardized method for measuring usability. With over 1,300 references in publications, SUS is widely used in the UX industry for its simplicity, effectiveness, and adaptability across different systems.
Is the System Usability Scale still relevant?
Yes, the System Usability Scale remains highly relevant as a reliable and standardized method for measuring usability. With over 1,300 references in publications, SUS is widely used in the UX industry for its simplicity, effectiveness, and adaptability across different systems.
What is a good System Usability Scale score?
A SUS score above 68 is generally considered above average. However, it is most effective when used to compare different versions of a design, benchmark against competitors, or evaluate "best practice" assets.
Can I use a System Usability Scale template?
Yes, a System Usability Scale template can streamline your usability testing process. Userlytics provides preformatted SUS tasks with automated scoring, making it easy to gather reliable results and focus on analysis.
How do I interpret System Usability Scale results?
SUS results can be interpreted using percentile rankings. For example: • Scores above 68: Above average usability • Scores below 68: Below average usability. These scores are best used to compare different designs or iterations rather than as absolute measures of usability.
Who created the System Usability Scale?
The System Usability Scale was developed by John Brooke in 1986 as a quick and simple way to assess system usability. It has since become an industry standard used worldwide.
Where can I find System Usability Scale examples?
Examples of System Usability Scale questionnaires and scoring methods can be found in UX research tools like Userlytics. These tools provide customizable templates, automated calculations, and visualizations of results.
What are the benefits of using the System Usability Scale?
1. Industry standard: Widely accepted across UX disciplines. 2. Quick and simple setup: Automated calculations with minimal effort. 3. Reliable results: Proven accuracy with small sample sizes. 4. Effective tool: Differentiates between assets with high and low usability.
Can I cite the System Usability Scale in my research?
Yes, the System Usability Scale can be cited in academic or professional research. Proper attribution is typically given to John Brooke, its creator.
How does Userlytics make SUS easier?
Userlytics offers preformatted SUS tasks with automated calculations and detailed results. The platform simplifies setup and analysis, allowing UX professionals to focus on creating impactful user experiences.
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