What is being measured
The test asks the browser to draw as fast as the display will accept for about three seconds, records the time of every frame, and reports the rate. It uses the median gap between frames rather than the average, because a single dropped frame would drag an average down by several hz and tell you a 144hz monitor is running at 138.
Results within two percent of a standard rate are reported as that rate. A browser reporting 59.94 on a 60hz panel is noise, not information, and rounding it to 60 is the honest answer.
Why your 144hz monitor says 60
This is the single most common result on this page, and it is almost never the monitor. In order of likelihood:
- The rate was never set. Buying a high refresh monitor does not switch it on. Windows and macOS both default to 60hz and leave the higher rate sitting in the display settings unused.
- The cable cannot carry it. An older HDMI cable or an HDMI port on the graphics card may cap out well below the panel rate at high resolution. DisplayPort is usually the right choice for a high refresh monitor.
- A laptop is running the test on its integrated graphics while the external monitor is wired to the discrete card, or the reverse.
- The browser window is on a different monitor than you think, and it is reporting that one.
- Battery saving is active. Most laptops drop the panel to 60hz on battery, and many phones do the same with adaptive refresh.
Browser measurement has limits
A browser can only report the rate it is being allowed to draw at, which is not always the rate the panel is scanning at. Variable refresh technologies change the rate continuously by design, so a number that wanders is expected rather than wrong. Some browsers also cap animation in background tabs, so keep this tab in the foreground while it measures. For an authoritative answer, the display settings in your operating system are the source of truth, and this test tells you whether the browser is really getting what those settings promise.