To provide a quick, subjective assessment of a system’s perceived usability by its users.
- Methodologies: Engineering, Product Design, Project Management
SUS (System Usability Scale)

SUS (System Usability Scale)
- Design Evaluation, Design Thinking, Quality Assurance, Quality Management, Usability, User experience (UX), User Interface (UI), User Testing, User-Centered Design
Objective:
How it’s used:
- A 10-item questionnaire with five response options for respondents, ranging from Strongly Agree to Strongly Disagree. Scores are converted to a 0-100 scale.
Pros
- Simple and quick to administer and score; provides a single, easily understandable usability score; widely used and benchmarked.
Cons
- Provides a subjective measure, not diagnostic of specific usability problems; scores can be influenced by user expectations and context.
Categories:
- Product Design, Quality
Best for:
- Quickly assessing the overall perceived usability of a system.
The System Usability Scale (SUS) is particularly advantageous in various sectors, including software development, healthcare technology, consumer electronics, and e-commerce, as it serves as a reliable tool for gauging user experiences across different applications. Used typically in the later phases of the design process, such as user testing or post-deployment evaluations, SUS can reveal how users perceive the usability of a product or system after real interactions, ensuring that design decisions align closely with user needs. Participation in SUS assessments is often open to a diverse range of stakeholders, including end-users, designers, usability researchers, and product managers, which helps in gathering varied perspectives on usability while promoting collaboration. Its straightforward nature allows teams to administer the questionnaire rapidly, yielding results that are easily interpretable and comparable against established benchmarks, enabling organizations to identify usability issues early or confirm successful design implementations. This methodology is extensively referenced in usability research and is frequently adopted in academic studies, making it well-suited for grant applications and compliance with industry standards focused on user-centered design practices, reflecting a commitment to delivering high-quality experiences that prioritize user satisfaction. The flexibility of the SUS allows it to be integrated into iterative design processes, where continuous user feedback contributes to product refinement, ultimately enhancing the likelihood of market success for innovative products.
Key steps of this methodology
- Administer the SUS questionnaire to users after interacting with the product.
- Ask respondents to rate each of the 10 items on a 5-point Likert scale (Strongly Agree to Strongly Disagree).
- For odd-numbered items, subtract 1 from the user response to obtain a score from 0 to 4.
- For even-numbered items, subtract the user response from 5 to obtain a score from 0 to 4.
- Sum the adjusted scores for all 10 items to get a total score.
- Multiply the total score by 2.5 to convert it to a 0-100 scale.
Pro Tips
- Incorporate SUS scores with qualitative feedback to identify specific usability issues and areas for improvement.
- Compare SUS results with established benchmarks in your domain to contextualize usability performance against industry standards.
- Use multiple iterations of testing with SUS throughout the design process for continuous feedback and refinement of the user experience.
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