Method SUS: A Simple Way to Evaluate the Usability of a Digital Product

The SUS method was created in 1986 by John Brooke and over the decades has become the «gold standard» in UX research thanks to its simplicity, speed, and versatility.

Where the SUS method is used

The methodology for evaluating interface usability using SUS is widely used in:

• IT projects — from startups to CMS platforms and enterprise systems.
• Mobile applications — to measure clarity and ease of navigation.
• SaaS services — to identify problem areas before releases or updates.
• Online stores — to understand how convenient it is to place an order or search for a product.
• UX/UI research — as a quick method of preliminary diagnostics before in-depth tests.

SUS provides a clear numerical usability score that is easy to interpret, compare with benchmarks, and track against the dynamics of previous versions.

Why SUS is convenient and useful

The main advantages of the SUS method:

• Quick to complete, easy to analyze. 10 short questions — that is 1–2 minutes from the user and a simple mathematical formula for the team.
• Universal and comparable. You can measure everything: from websites to electronic devices, and compare versions, products, and releases — one index that everyone understands.
• Covers key aspects of UX. SUS takes into account not only ease of use, but also user confidence, interface consistency, and the need for training.

Evaluating interface usability with QForm

QForm makes it easy to implement the System Usability Scale method into research and development processes:

• Intuitive visual builder for creating SUS surveys.
• Flexible survey setup without code: scales, hints, logical transitions.
• Multiple distribution options: email campaigns, public links, embeddable widgets.
• Automatic data collection and visualization: charts, tables, usability indexes.
• Export and integrations: data transfer to Excel and BI systems via API.

This solution saves time for UX researchers, product teams, and analysts, helping them obtain standardized interface usability data faster — and immediately turn it into action.

How the SUS method works: structure and scoring principle

Structure of a SUS survey

The System Usability Scale method consists of 10 statements that alternate between positive and negative wording. This is done to reduce bias and increase the reliability of the result. The user rates each statement on a 5-point scale (Likert scale):

1. Strongly disagree
2. Rather disagree
3. Neither agree nor disagree
4. Rather agree
5. Strongly agree

Most statements relate to aspects such as ease of learning the product, interface consistency, confidence while using it, need for assistance, and frequency of potential use.

Examples of typical SUS questions

The survey includes wording such as:

• «I think that I would like to use this product frequently»
• «I found the product unnecessarily complex»
• «I felt confident using this product»
• «I needed to learn a lot of things before I could get going with this product»

These questions are the foundation of the standard: thanks to them, SUS makes it possible to build an objective understanding of interface usability and the emotional perception of the interaction.

How the final SUS score is calculated

The response processing technique is simple and standardized:

1. Each answer is assigned a numerical value (from 0 to 4), while negative questions are reversed.
2. The final sum is multiplied by 2.5 — producing a score in the range from 0 to 100.

For example: if a respondent gives a «5» for a positive question — this equals 4 points, and a «1» for a negative question — also equals 4 points.

This approach makes it possible to obtain a numerical indicator that:

• is easy to interpret;
• is comparable between products and releases;
• is widely used for analysis in UX projects, research, and business reports.

How applying SUS helps when working on an interface

Using SUS results, product and UX teams can:

• Quickly identify interface weaknesses even before large-scale development;
• Compare different design versions;
• Track user reactions to updates;
• Determine priority areas for improvements.

SUS turns subjective user experience into measurable metrics — which means it makes UX decisions more deliberate and effective.

Examples of using SUS in practice

In which products SUS is used most often

System Usability Scale — is a universal tool. It is applied across a wide range of digital and physical interfaces, including:

• Mobile applications: helps assess how intuitive the interaction scenario is for the user and whether screen navigation is convenient;
• SaaS platforms and web services: identifies problematic stages in onboarding, feature usage, or analytics modules;
• Online stores: shows how easily a buyer finds a product, adds it to the cart, and pays for it;
• Enterprise CRM and ERP systems: helps understand how convenient the system is for employees from different departments;
• Interactive terminals and kiosks: evaluates the accessibility and logic of the interface for visitors;
• Prototypes of new features or MVP products.

Example of working with SUS in a team

Suppose a company has launched a new module in its B2B service and wants to understand how convenient it is for clients. The UX design team gathers a group of users, sends a SUS survey through an online form, and receives results with an average score — for example, 62/100. This is below the desired level, and such a score indicates insufficient usability.

After analyzing comments and negatively rated questions, the team finds problem areas — for example, difficulty configuring parameters or a lack of explanations. After the interface is updated, a repeat survey is conducted — the SUS score rises to 78, confirming that the changes improved the user experience.

How SUS speeds up the decision-making process

Using the SUS-based interface usability evaluation method helps teams:

• Make decisions based on data, not subjective opinion — an objective score shows the real state of UX.
• Reduce research preparation time — SUS is easy to integrate and process.
• Increase stakeholder trust in changes — a numerical result is easier to interpret and use in reporting.
• Build regular improvement cycles — the results of the current version can easily be compared with previous releases.

Thus, the SUS method complements qualitative research and helps products grow faster — relying on real feedback and standardized metrics.

How to create and conduct a SUS survey: step-by-step algorithm

1. Define the goal and audience of the survey

Before conducting the System Usability Scale, it is important to understand exactly what you want to measure:

• The usability of a new interface or an existing feature?
• The effectiveness of an improved user journey?
• Differences between product versions?

Also define whom to invite to the survey: newcomers, active users, internal teams, or external clients.

2. Prepare standardized SUS questions

Use the 10 SUS statements without changes — this is important so that you can compare your results with industry indicators. The questions should alternate between positive and negative wording.

Example:

• «I think that I would like to use this product frequently»
• «I found the product unnecessarily complex»
  ...and so on — up to 10 statements.

3. Choose a survey channel

Choose where it will be most convenient for the user to respond:

• Email campaign;
• Displaying the form after completing a scenario (purchase, registration);
• Survey via link;
• Pop-up window on a website or in an application.

Important: do not interrupt the user — place the survey at natural interaction points.

4. Collect responses and calculate the SUS result

Collect the data and convert the answers into a numerical score on a 100-point scale. This can be done manually or using a platform with automatic calculation.

5. Interpret the results and draw conclusions

A SUS score from 0 to 100 is divided into ranges:

• 0–50 – critically low usability
• 50–70 – there are problems, refinement is required
• 70–85 – good usability, optimization is possible
• 85–100 – excellent usability, can be used as a reference

Based on the analysis, create a list of improvements: what to improve in UX, which stages to simplify, where to add hints or visual accents.

6. Conduct a repeat study

Changed the interface? Conduct SUS again. Comparing the results will show whether the improvement was truly successful and whether the new version works as intended.

Regular SUS cycles allow you to maintain a high level of UX quality without involving large research resources every time.

How to interpret SUS results: scales, benchmarks, and practical meaning

How to convert SUS data into a score

After respondents have answered the 10 statements, each of their answers is converted into a numerical result:

• For positive statements (1, 3, 5, 7, 9):
  Score = (rating – 1)
• For negative statements (2, 4, 6, 8, 10):
  Score = (5 – rating)

All results are summed, and the total is multiplied by 2.5 — this is the final SUS interface usability score in the range from 0 to 100.

Ranges and what they mean

Comparison with industry standards

One of the main advantages of SUS is the ability to compare results with other products and versions. For example:

• Average SUS across the SaaS product market: 68
• Benchmark level for mobile applications: 80+
• Minimum threshold for starting beta: 65

This helps you understand not only your own progress, but also your product’s position in the competitive context.

How to extract valuable insights from SUS

A single final number is only the surface layer. To benefit from it, it is important to:

• Look at which questions received the lowest scores — this will reveal obvious pain points;
• Analyze differences between user types (newcomers vs. experienced users);
• Supplement the results with qualitative data — comments, interviews, or usability tests.

Using SUS in product work

SUS results allow you to:

• Prioritize UX tasks: focus on what interferes with users the most;
• Justify changes: use clear numbers to show the advantages of a redesign or interface simplification;
• Maintain regular UX audits of the product: track progress after releases and receive feedback in a single format.

System Usability Scale — is ideal where you need evidence-based and fast user experience measurement that all product roles can easily understand: from designers to top management.

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Conclusion

System Usability Scale (SUS) — is a simple but powerful tool that allows you to objectively measure the usability of any digital product. Its versatility, standardization, and ease of implementation have made this method the gold standard in UX research. Regular use of SUS allows you to:

• Receive timely feedback from real users
• Identify interface growth points in time
• Make decisions based on data rather than assumptions
• Improve product quality — and, as a result, audience retention and loyalty

SUS is especially valuable because it is suitable for products at any stage of development — from early prototypes to mature releases. You can easily track how the perception of usability changes over time and, if necessary, compare the product with competitors or previous versions of the interface.

To ensure that implementing SUS does not distract the team from its core work and delivers measurable results, it is important to automate the process of collecting and analyzing data. Platforms for creating forms and questionnaires (including QForm) allow you to set up a survey in just a few minutes, send it to users, and receive a clear report with score interpretation. This gives every company — from a startup to a corporation — the opportunity to embed usability metrics into its product practice.

Implement SUS, measure, improve, repeat.