What is the system usability scale? 

One of the best ways to evaluate the performance and effectiveness of your product or service is through usability testing and the system usability scale (SUS). This approach provides valuable feedback from people who are using your solution. They answer a series of 10 questions, and you can use the results to calculate a numerical usability score.

For example, say you’re developing a project management SaaS solution or seeking to improve an existing one. You’d give users a set of tasks to complete with the tool, observe their interactions, and note how they experience your product. Then you’d provide them with the 10-question system usability survey. This process allows you to determine usability issues and plan for improvements, based on real-time user feedback.

In this article, we’ll define what the system usability scale is, offer guidance on how to create a system usability survey, share 10 system usability questions, and clarify how to calculate the SUS score. We’ll also share the many Jotform resources available that can help you create and administer your own SUS survey.

How the system usability scale works

The system usability scale (SUS) is a tool for measuring the usability of a product, solution, or system, according to responses to a 10-item Likert scale questionnaire. There are five answer options for each question that range from strongly disagree to strongly agree. John Brooke created this tool in 1986 to identify usability issues with software, hardware, websites, mobile devices, and other types of design, products, and services.

Because usability tests are conducted with real users (as opposed to members of your in-house team, for example), the feedback is considered more effective at assessing product or design challenges, allowing you to create or improve a product so that it solves your users’ problems in a way that appeals to them.

The system usability scale can help measure efficiency, ease of use, and user satisfaction, as well as how intuitive (or difficult) your product or solution is to understand.

How to design a usability survey

Delivering a usability survey involves first creating and setting up the usability testing process, then administering the system usability scale (SUS) questionnaire to assess the usability of your products or services.

Here is a brief overview of the process:

  1. Determine your target audience and the goal of the test. Identify the segment of your audience you wish to test, the features or processes you’re seeking feedback on, the tasks you want users to complete, and the insights you’re hoping to gather. 
  2. For example, going back to our earlier example of a SaaS project management tool, you may choose to assess how easy it is for a segment of users aged 35–49 to set up a project, a collaboration, or an individual task using your software.

  1. Develop evaluation measures. Determine the usability metrics you plan to track — such as time on task, task completion rate, bounce rate, the number of participants who followed the optimal work process flow, the user satisfaction score, and so on.
  1. Create a usability testing script. Include the tasks users will execute and instructions for completing them. The instructions should avoid using leading language (i.e., “Choose our powerful collaboration feature and set up a collaboration with a colleague.”) and should follow a logical sequence of tasks.
  1. Recruit test participants. As mentioned in the first step, you’ll likely choose a particular segment of your audience to participate in the usability test, depending on the product or solution features you plan to test. You can invite existing customers to participate by sending emails to that segment of your customer database, or you can invite those who’ve opted into your email list but haven’t purchased your product yet. The choice depends on your goals and objectives for testing.
  2. Once the usability test is complete, share the SUS questionnaire with participants. The next section will cover questions to ask on a system usability scale questionnaire.

How to phrase your system usability scale questions

You can use system usability scale questions to gauge usability for hardware and software, applications, websites, and other products and services. All system usability scale questions follow essentially the same format, and you can modify them to fit the software or other design or tech solution you’re testing.

Using the previous example of a project management software tool, instruct participants to state their level of agreement or disagreement on a five-point Likert scale, from strongly disagree to strongly agree, for the following 10 statements:

  1. I think I would use this project management tool frequently.
  2. I found this project management tool unnecessarily complex.
  3. I thought this tool was simple and easy to use.
  4. I think I would need tech support to use this project management tool.
  5. I found the various functions in this tool well integrated.
  6. I thought there was too much inconsistency in this tool.
  7. I think most people could learn to use this tool very quickly.
  8. I found this tool cumbersome/awkward to use.
  9. I felt very confident using this tool.
  10. I think I would need to learn a lot of things before I could use this tool.

How to calculate the SUS score

To calculate the SUS score, add the numbers for responses to the odd-numbered questions (1, 3, 7, 9) and subtract 5 from that total to get your odd score.

Then add the numbers for responses to the even-numbered questions (2, 4, 6, 8, 10) and subtract that total from 25 to get your even score.

Add these scores together and multiply that number by 2.5 to get your final SUS score out of 100.

Here’s how that looks in practice:

Let’s say the odd-numbered responses were 4, 3, 4, 3 and 5. The total is 19. Then 19 – 5 = 14.

And the even-numbered responses were 2, 2, 3, 1, and 2. The total is 10. Then 25 – 10 = 15.

14 + 15 = 29 x 2.5 = 72.5

This gives you a final SUS score of 72.5.

A total SUS score over 68 is considered above average, indicating better usability, while a lower score may point to usability issues.

Advantages and disadvantages of using the system usability scale

There are several advantages of the system usability scale:

  • The system usability scale questionnaire is easy to administer and intuitive for users to understand.
  • You can process the data and calculate scores quickly and easily, as it relies on responses to just 10 questions.
  • Application of the SUS is versatile and adaptable — it’s helpful for measuring the usability of hardware, software, websites, systems, and other products and services.
  • It’s inexpensive to execute compared to other similar methods.
  • It pinpoints issues based on real-time user feedback.

There are also a few disadvantages:

  • It can’t provide specific information on product or service weaknesses.
  • It’s not effective if you want to compare two systems and get specific guidelines for taking action.
  • Participant responses are subjective, measuring only perceived usability.
  • It’s not a diagnostic tool. You’ll receive a usability score, but you’ll need to employ an additional research method to gather data on how to improve your score.

How Jotform makes SUS surveys easy

Jotform allows users to create and customize surveys with our free online survey maker. Easily design a SUS survey with our drag-and-drop, no-code builder, and then distribute your survey by embedding it on a website accessible to your usability testing participants. You can also choose to share it via email or a direct link and start collecting responses instantly.

Jotform integrates with several data analysis tools and platforms, giving users the ability to export SUS data to Excel and Google Sheets, making it easy to view, manage, and analyze data quickly. For more detailed analysis, check out Jotform’s other analytics and reporting integrations.

If you need to export your data all at once, you can do that with the Export Datafeature. Want to understand more about form analytics and collecting user info? Check out our guide on using Jotform’s built-in form analytics.

With Jotform Tables, you have the ability to view, edit, print, flag, delete, and download form submissions. It’s the central place to manage your form submission data. We also have a guide on how to view form submissions if you want to learn more.

Need even more survey options? Jotform has you covered there, too, with more than 1,300 survey templates to choose from.

Photo by Ron Lach

Kimberly Houston is a conversion-focused marketing copywriter. She loves helping established creative service providers attract and convert their ideal clients with personality-driven web and email copy, so they can stand out online, and get more business, bookings, and sales.

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