SUS stands out as an easy standardized metric designed to assess the perceived usability and learnability of various platforms, including websites, software, mobile applications, and interactive voice-response systems.

For its simplicity and accuracy, SUS is among the most adopted UX measurements and it is a valuable quantitative tool for anyone trying to benchmark their user experience. Although, SUS is not a diagnostic tool.

One of the biggest advantages of measuring SUS is that you can monitor how it evolves over time by keeping track of it. In this way, you can see if your actions (redesign, changes, new features) or even your non-actions (age, competition) affect the perceived usability of your product.

Can be linked to the NPS score.

SUS is a post-test questionnaire which means it is administered at the end of a usability session or after a user has used your solution over a period of time. They reflect on how users perceive the usability of the product as a whole.

SUS uses a short, 10-item questionnaire administered at the end of a usability test to calculate the usability score of the digital product. Users respond to each question on a 5-point scale from "Strongly disagree" to "Strongly agree." These answers are then used to generate an extremely reliable overall usability score for the product.

This metric does not tell us why users struggle with a design, nor do they provide direct insights as to how we can improve it. They simply are a way of keeping track of how the users feel about the experience of using a product or service.

Items 1, 3, 5, 7, and 9 are positively worded statements and measure satisfaction with the system. Items 2, 4, 6, 8, and 10 are negatively worded statements and measure dissatisfaction with the system. The SUS uses a five-point Likert scale ranging from strongly agree to strongly disagree to capture the user's level of agreement or disagreement with each statement.

Overall, the SUS is a comprehensive measure of usability that includes aspects such as learnability, efficiency, and satisfaction, all of which can influence the overall usability and user experience of a system.

Covers USABILITY CRITERIA.

A SUS study can be run at any stage of a product's lifecycle, from the early stages of design and development to post-launch evaluation.

Here are some examples of when a SUS study might be appropriate:

1. Early stage design: A SUS study can help to identify usability issues and inform design decisions before development begins.

2. Prototype testing: A SUS study can be used to evaluate the usability of a prototype and gather feedback to refine the design.

3. Pre-launch testing: A SUS study can be used to evaluate the usability of a product before it is released to the public and make any necessary changes to improve the user experience.

4. Post-launch evaluation: A SUS study can be used to evaluate the usability of a product after it has been released to the market and identify areas for improvement.

5. Competitive analysis: A SUS study can be used to compare the usability of a product to its competitors and identify opportunities for differentiation.

SUS score can influence customer loyalty. Research has shown that there is a positive correlation between SUS scores and user satisfaction, and customer satisfaction is a key driver of customer loyalty.

When a user has a positive experience with a product or service, they are more likely to become loyal customers and recommend the product to others. A high SUS score indicates that users perceive the system as easy to use, efficient, and effective, which can lead to higher user satisfaction and, in turn, higher customer loyalty.

Furthermore, a high SUS score can help to differentiate a product from its competitors and create a positive brand image, which can also contribute to customer loyalty.

In summary, the SUS score can indirectly influence customer loyalty by measuring the usability and user experience of a product, which can impact user satisfaction and brand loyalty.

This metric does not tell us why users struggle with a design, nor do they provide direct insights as to how we can improve it. They simply are a way of keeping track of how the users feel about the experience of using a product or service.

Pros

• Quick and easy to administer: The SUS questionnaire is relatively short and straightforward, and it can be administered quickly and easily to a large number of participants. The biggest advantage is that it's such an old scale that there is a large amount of industry-wide data available to help benchmark your score and understand it in the context of your peers and competitors.

• Standardized and validated: The SUS is a standardized questionnaire that has been validated through numerous studies, making it a reliable and valid tool for measuring usability. It has a free normed database of scores.

• Comprehensive measure of usability: The SUS questionnaire measures multiple aspects of usability, including learnability, efficiency, and satisfaction, providing a comprehensive measure of the overall user experience. And it also correlates strongly with a much simpler metric, the single-question Net Promoter Score.

• Benchmarks usability: The SUS provides a benchmark for comparing the usability of different systems, which can be useful for evaluating the effectiveness of design changes and for competitive analysis. SUS is also considered a technology-agnostic questionnaire, meaning the items aren't specific to any technology or platform.

Cons

• Limited scope: While the SUS provides a comprehensive measure of usability, it may not capture all aspects of the user experience, such as emotional responses, aesthetics, or engagement. Plus, it doesn't address usefulness or utility.

• May not be suitable for all systems: The SUS questionnaire may not be suitable for measuring the usability of complex or specialized systems, such as medical equipment or industrial machinery.

• May not capture context-specific issues: The SUS questionnaire is a general measure of usability and may not capture context-specific issues that are relevant to particular users or tasks.

• May not provide detailed feedback: The SUS questionnaire provides a numerical score and may not provide detailed feedback on specific usability issues that need to be addressed.

• Bias feedback: User impressions of the experience as a whole are subject to the peak-end effect (that is, the most intense and last parts of the experience, either positive or negative, impact participants' recollections and evaluations the most).

The questionnaire consists of 10 items, and participants rate each item on a 5-point Likert scale from 'Strongly Disagree' to 'Strongly Agree'. The questions are as follows:

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 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.

TIP: I recommend adding demographic questions at the beginning or end of the questionnaire such as geography, age, education, experience with the product, and so on, so you may correlate your SUS score with factors that may influence the final score. The calculator is prepared to deal is this type of data in the Data tab of the spreadsheet.