Knowledge Base: What is Apdex?

Apdex is an industry standard for measuring the satisfaction of a user of an application or service. It's a simplified Service Level Agreement (SLA) solution that gives application owners better insight into how satisfied users are, in contrast to traditional metrics like average response time, which can be skewed by a few very long responses. Here's how Apdex works. The application owner defines a response time threshold called T. All responses handled in T or less time satisfy the user. For example, if T is 1.2 seconds and a response completes in 0.5 seconds, then the user was satisfied. All other responses dissatisfy the user, however there are two levels of dissatisfaction. Responses greater than T and less than or equal to 4T are tolerated by the user. Responses greater than 4T frustrate the user.

The Apdex score for an application is computed with a simple formula that returns a satisfaction ratio. A score of 1.0 means all responses were satisfactory. A score of 0.0 means none of the responses were satisfactory. Tolerating responses half satisfy a user. For example, if all responses are tolerating then the Apdex score would be 0.50.

For more about Apdex, watch our 3-minute screencast or see the Apdex website.