{"id":3512,"date":"2026-05-27T08:35:15","date_gmt":"2026-05-27T08:35:15","guid":{"rendered":"https:\/\/loadfocus.com\/blog\/?p=3512"},"modified":"2026-05-27T08:35:16","modified_gmt":"2026-05-27T08:35:16","slug":"what-are-virtual-users-in-load-testing","status":"publish","type":"post","link":"https:\/\/loadfocus.com\/blog\/2026\/05\/what-are-virtual-users-in-load-testing","title":{"rendered":"What are Virtual Users (VUs) in Load Testing? Definition + Examples"},"content":{"rendered":"<\/span> 7<\/span> minutes read<\/span><\/span>\n

Virtual users (VUs) are the simulated humans that hit your system during a load test. They’re the load. Where real users come from browsers and apps, VUs come from a test harness. JMeter threads, k6 worker goroutines, Locust greenlets. Each VU sends requests, waits for responses, sometimes pauses (“think time”), and repeats. Aggregate enough VUs and you get traffic that looks like a real audience.<\/p>\n\n\n\n

This post covers what virtual users actually are, how they differ from real users and from requests-per-second (RPS), how the major tools model them, and the common misconfigurations that make VU-based test results lie.<\/p>\n\n\n\n

The quick answer<\/h2>\n\n\n\n

VUs are the test-harness primitive that simulates concurrent activity. They’re how you express load.<\/p>\n\n\n\n

<\/th>Virtual Users (VUs)<\/th>Real Users<\/th>RPS (Requests Per Second)<\/th><\/tr><\/thead>
What it is<\/strong><\/td>A test thread\/process simulating one concurrent human<\/td>An actual human in front of a browser\/app<\/td>A rate of work the system completes<\/td><\/tr>
Controlled by<\/strong><\/td>You (the test design)<\/td>Whoever your audience is<\/td>Emerges from VUs \u00d7 request rate \u00d7 think time<\/td><\/tr>
Used for<\/strong><\/td>Expressing test load<\/td>Production traffic<\/td>Measuring server-side capacity<\/td><\/tr>
Has think time?<\/strong><\/td>Optional, configurable<\/td>Yes, between actions<\/td>N\/A. It’s a rate<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

For a deeper dive into how VUs translate to RPS in practice, see understanding the difference between virtual users and requests per second<\/a>.<\/p>\n\n\n\n

What is a virtual user?<\/h2>\n\n\n\n

A virtual user is a unit of concurrent simulated activity in a load test. Mechanically, it’s typically one thread (in JMeter), one goroutine (in k6), or one greenlet\/coroutine (in Locust) that:<\/p>\n\n\n\n

    \n
  1. Logs in (or starts with a pre-authenticated session).<\/li>\n
  2. Walks through a defined user flow. Checkout, search, browse, whatever the script defines.<\/li>\n
  3. Sends HTTP requests, waits for responses, measures latency.<\/li>\n
  4. Optionally pauses for “think time” between actions (3-10 seconds is realistic).<\/li>\n
  5. Loops, either through the same flow again or exits.<\/li>\n<\/ol>\n\n\n\n

    100 VUs running concurrently = 100 of these threads\/coroutines running in parallel. To the system under test, they look indistinguishable from 100 real users hitting the service simultaneously.<\/p>\n\n\n\n

    The point of a load test<\/a> is to express expected production load as some number of VUs, then watch how the system responds.<\/p>\n\n\n\n

    VUs vs real users<\/h2>\n\n\n\n

    VUs are useful precisely because they’re predictable in ways real users aren’t:<\/p>\n\n\n\n