Start with display settings
Select the correct monitor in your operating system’s display settings and inspect its active refresh mode. A panel sold as 144 Hz may be operating at a lower setting. Available modes can depend on the cable, port, adapter, dock and selected resolution.
Measure the browser on that display
Move the window to the intended monitor and open the Refresh Rate Test. Keep it in the foreground. The page estimates cadence from animation-frame timestamps; background tabs and power-saving modes can throttle that scheduling.
Understand the units
At 60 Hz, a refresh interval is approximately 16.7 ms; at 120 Hz it is 8.3 ms; at 144 Hz it is 6.9 ms. These intervals are not pixel response time and do not measure end-to-end input lag. A game’s FPS is also a separate quantity.
Investigate a lower reading
Repeat with unnecessary browser work closed. Confirm that the window is on the intended display and check the active mode again. Variable refresh and performance limits can alter the result. A browser estimate alone should not decide whether a monitor, cable or GPU is defective.
Check related display questions
Use the Screen Resolution Checker to inspect browser-reported CSS dimensions and scaling. Use the Dead Pixel Test for visual panel inspection. Neither tool reads every hardware specification, and a high Hz reading does not establish colour accuracy or pixel health.