Error Rate: A Simple Metric That Reveals Major Usability Problems

By Philip Burgess | UX Research Leader

When users struggle with a product or service, the signs often show up in their mistakes. One of the clearest ways to spot these issues is by measuring the error rate. This simple metric can uncover major usability problems that might otherwise go unnoticed. Understanding and tracking error rate helps designers and developers create smoother, more intuitive experiences.

What Is Error Rate and Why It Matters

Error rate measures how often users make mistakes while interacting with a system. These mistakes can be anything from clicking the wrong button, entering invalid data, or failing to complete a task. By calculating the percentage of errors compared to total attempts, teams get a clear picture of where users struggle.

Why focus on error rate? Because it directly reflects the user’s experience. A high error rate signals confusion, frustration, or poor design. It points to parts of the interface that need improvement. Unlike subjective feedback, error rate provides objective data that teams can act on.

How to Measure Error Rate Effectively

Measuring error rate requires careful planning and clear definitions. Here are key steps to follow:

• Define what counts as an error

Not every mistake is equal. Decide which actions qualify as errors based on your goals. For example, entering a wrong password might be an error, but hesitating before clicking a button might not.

• Choose the right tasks to test

Select tasks that represent common or critical user goals. This ensures the error rate reflects real-world challenges.

• Collect data systematically

Use usability testing sessions, analytics tools, or user recordings to gather error data. Make sure to capture enough samples for reliable results.

• Calculate error rate clearly

Divide the number of errors by the total number of attempts, then multiply by 100 to get a percentage. For example, if 15 errors occur in 100 attempts, the error rate is 15%.

Tracking error rate over time also helps monitor improvements after design changes.

Error messages displayed on a form submission screen

Common Usability Problems Revealed by High Error Rates

High error rates often highlight specific usability issues. Some common problems include:

• Confusing navigation

Users click wrong links or buttons because menus are unclear or inconsistent.

• Poor form design

Forms with unclear labels, missing instructions, or strict validation cause frequent input errors.

• Unclear feedback

When the system does not clearly explain errors or next steps, users repeat mistakes.

• Complex workflows

Tasks that require many steps or decisions increase the chance of errors.

For example, an e-commerce checkout page with unclear field labels and no inline validation might show a 20% error rate in address entry. This signals a need to simplify the form and provide better guidance.

Using Error Rate to Improve Design

Once you identify areas with high error rates, use the data to guide improvements:

• Simplify interfaces

Remove unnecessary options and clarify labels to reduce confusion.

• Add helpful feedback

Provide clear error messages and suggestions to help users correct mistakes quickly.

• Test alternative designs

Run A/B tests to compare versions and see which reduces errors.

• Train users when needed

For complex systems, offer tutorials or tooltips to guide users.

By focusing on reducing error rate, teams improve usability and user satisfaction. Lower error rates often lead to faster task completion and fewer support requests.

Participant performing tasks during a usability testing session

Practical Examples of Error Rate Impact

Consider a mobile banking app that tracks login errors. If 30% of users fail to log in on the first try, this high error rate suggests problems with password entry or authentication flow. The team might respond by simplifying password requirements or adding biometric options.

In another case, a software company noticed a 25% error rate in a file upload feature. Users often selected wrong file types or missed required fields. After redesigning the upload form with clearer instructions and file type filters, the error rate dropped to 8%.

These examples show how error rate highlights real pain points and guides targeted fixes.

Final Thoughts on Using Error Rate

Error rate is a straightforward but powerful metric for uncovering usability problems. It provides clear evidence of where users struggle and helps prioritize design improvements. By defining errors carefully, measuring consistently, and acting on the data, teams can create more user-friendly products.