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BenchRush → Browser refresh rate vs monitor Hz
Display timing guide

Browser refresh rate vs monitor Hz

The browser can measure animation callback cadence, not read your monitor electronics directly. Frame time is the useful bridge between the two numbers.

Frame time is the useful bridge

The BenchRush refresh-rate test samples requestAnimationFrame() intervals. Roughly, 60 Hz corresponds to 16.67 ms per frame, 120 Hz to 8.33 ms, 144 Hz to 6.94 ms, 165 Hz to 6.06 ms and 240 Hz to 4.17 ms. Real samples vary, so the page reports a median cadence and timing spread rather than pretending every frame is identical.

Why browser Hz can differ from the display setting

The operating system chooses a display mode, but the browser still has its own scheduling and compositor path. Background throttling, power saving, variable-refresh behavior, window placement across displays, heavy CPU/GPU work and a hidden tab can all change the callback pattern visible to JavaScript.

Make the test repeatable

  1. Keep the tab visible and focused.
  2. Use the same display and browser window position.
  3. Close or pause unusually heavy background work.
  4. Confirm the operating-system display mode before the run.
  5. Take several samples and compare the median range rather than one result.

If you expected 144 Hz but see about 60 Hz

First check the operating-system display setting and cable/display configuration. Then make sure the browser window is actually on the high-refresh display. Laptop power modes and remote-desktop sessions can also change presentation cadence. If another browser shows the same 60 Hz-like pattern, investigate the system/display configuration before treating BenchRush as the cause.

If the number jumps around

Look at timing spread as well as the rounded Hz class. A stable 6.8–7.1 ms region tells a different story from intervals that repeatedly jump between short and long frames. High spread can reflect workload or scheduling noise even when the median is near the expected refresh class.

Do not turn this into a monitor certificate

requestAnimationFrame() is designed to synchronize browser animation with repaint opportunities. It is not a hardware probe and cannot guarantee the panel's internal scanout, response time or variable-refresh behavior. Use the monitor's own information screen, operating-system settings or vendor tools when you need hardware confirmation.

Technical reference

MDN documents requestAnimationFrame() and notes that callback frequency generally follows the display refresh rate but can be paused or reduced in background contexts. BenchRush measures the browser-visible callback cadence and labels it accordingly.