Monitor refresh rate test

How to run the test

1. Open the page on the screen you want to test. Close other heavy tabs and apps.
2. Keep the tab in front and do not move other windows for three seconds while it measures.
3. Read Frames per second and Nearest common rate. Press Measure again (3 s) a couple of times, also in Full screen, and compare.

Reading the result

• Frames per second is based on the median time between frames, so a few slow frames do not change it much.
• Nearest common rate rounds that value to a standard refresh rate, for example 143.9 fps to 144 Hz.
• Late frames counts frames that took more than 1.5 times the usual interval. A few are common; many mean the browser is struggling or being throttled.
• Frame-time jitter is the spread of the normal frame intervals in milliseconds. Low values mean an even cadence.
• The bar alternates black and white every frame. At a steady rate it looks like an even grey; flicker means frames are being missed.

If the value is lower than expected

• Check the refresh rate selected in your operating system's display settings. New monitors often start at 60 Hz.
• The cable, port or adapter may not support the higher rate at your resolution. Try the cable and port recommended in the monitor's manual.
• Battery saver modes, laptops running on battery and some browsers limit animation to a lower frame rate.
• With several monitors at different rates, the browser may follow another monitor's rate. Test with the window on the monitor in question, or with only that monitor connected.
• Variable refresh rate (G-Sync, FreeSync, Adaptive-Sync) and remote desktop sessions can also change what the browser reports.

This is an estimate of what the browser draws, not a hardware measurement of the panel, and it says nothing about response time. To see the effect of response time, use the monitor ghosting test; to check whether an overclocked monitor skips frames, use the frame skipping test.