System Usability Scale (SUS)

What is the System Usability Scale (SUS)?

The System Usability Scale (SUS) is a widely used tool to assess the usability of a system, application, or product. Created in 1986 by John Brooke, SUS is a simple, ten-item questionnaire that provides a global view of subjective assessments of usability. Each item is scored on a five-point Likert scale, from strongly agree to strongly disagree. The total score gives a quick and effective estimate of the product's usability, ranging from 0 to 100, with higher scores indicating better usability.

When is the System Usability Scale (SUS) Used?

SUS is used when a product, system, or application needs a quick assessment of its usability from the user’s perspective. It is often employed after user testing sessions, beta testing phases, or when a product has been developed to a point where its usability can be critically evaluated. It is ideal for gathering feedback from end users to identify usability issues before the product launch.

Pros of Using the System Usability Scale (SUS)

Simplicity and Speed: SUS is easy to administer and takes only a few minutes for users to complete. It provides a quantitative measure of usability in a short time.
Widely Recognized: Being a standard tool in usability testing, its results are highly credible and widely accepted in the product development community.
Cost-Effective: SUS requires minimal resources and time to deploy, making it a cost-effective way to gather usability insights.
Comparability: Since SUS is a widely used measure, the scores can be compared across different products, systems, or updates.

Cons of Using the System Usability Scale (SUS)

Subjective Nature: While SUS provides quantitative results, they are based on subjective opinions, which may vary significantly depending on user expectations and experiences.
Limited Diagnostic Insights: SUS can tell you if there’s a usability problem, but it doesn’t provide detailed information about where or what the problems are.
Requires Larger Sample Sizes: The scale’s results can vary with smaller sample sizes, meaning larger groups are needed for more accurate and reliable data.

How is the System Usability Scale (SUS) Useful for Product Managers?

For product managers, SUS offers a quick and efficient way to gauge how users perceive the usability of their product. The scale helps in:

Measuring User Satisfaction: A product manager can get an early sense of how users feel about interacting with the product.
Benchmarking: By comparing SUS scores with industry standards or previous versions of the product, a product manager can evaluate whether usability is improving over time.
Identifying Trends: If a SUS score reveals lower usability, it prompts further investigation into specific areas of the product that may need rework, guiding future development priorities.

When Should the System Usability Scale (SUS) Not Be Used?

SUS should not be used:

For Detailed Analysis: If you need in-depth insights into specific usability issues, other methods like task analysis, eye-tracking, or direct user interviews may be more appropriate.
With Highly Specialized Products: In cases where the user base is extremely niche or specialized, the general questions in SUS may not align with the specific needs or expectations of the users.
As the Sole Measure: Relying exclusively on SUS may overlook other critical aspects of usability, such as accessibility or visual design, which also impact the user experience.

Related Terms

← All Terms

No	Title	Brief
1	Alpha Test	Initial testing of a product prototype within the developing company to identify potential defects.
2	Beta Test	Testing a new product prototype with actual users to discover potential defects before launch.
3	Brand Extension	A variation of a product that carries the brand name of the core product.
4	Prototype	A preliminary version of a new product used for research purposes.
5	Agile Development	A methodology emphasizing iterative development, where requirements and solutions evolve through collaboration between self-organizing cross-functional teams.
6	Scrum	An Agile framework for managing work with an emphasis on software development, involving roles such as Scrum Master, Product Owner, and Development Team.
7	Sprint	A set period during which specific work has to be completed and made ready for review in Agile frameworks like Scrum.
8	Minimum Viable Product (MVP)	A version of a new product that allows a team to collect the maximum amount of validated learning about customers with the least effort.
9	Continuous Integration (CI)	A practice in software engineering where team members integrate their work frequently, typically several times a day.
10	Definition of Done	A shared understanding of what it means for work to be complete, ensuring that nothing is left out and work meets the agreed quality.