Measure browser rendering cadence and compare the selected display mode with expectations.
How the measurement works
The browser calls requestAnimationFrame before each new frame. DeviceDoctor estimates the visible refresh cadence from the timing between these callbacks. The result can be lower than expected when the tab is in the background, the computer is under load or power saving is enabled.
- Keep the test tab visible and in the foreground.
- Connect a laptop to power.
- Select the intended refresh rate in operating-system display settings.
Why the result may not be a whole number
A result of 59.9 Hz is effectively the 60 Hz class, just as 119.8 Hz can represent a 120 Hz mode. Variable refresh rate and frame timing create small fluctuations. This measures browser rendering cadence, not the panel with laboratory hardware.
With multiple monitors, move the browser window to the display you want to test and restart the measurement. Remote desktop sessions can hide the real display cadence.