What this measures
Browsers draw a page in step with the display: when nothing holds them back, they draw one frame each time the screen refreshes. So a 144 Hz monitor usually gives about 144 frames per second here, and a 60 Hz one about 60. The test counts those frames for ten seconds after a one-second warm-up and shows the average, the typical time between frames, and how many arrived late.
Lower than your monitor's rating?
- Windows is set lower. Check Settings, System, Display, Advanced display, Choose a refresh rate. A 144 Hz monitor can be left at 60 Hz.
- The cable or port can't carry it. High refresh rates may need DisplayPort or a newer HDMI port and cable; check your monitor's manual.
- The browser is holding back. Browsers may draw fewer frames than the screen shows to save power or when the computer is busy, for example on battery.
- Variable refresh. With G-SYNC or FreeSync, the screen follows the frames, so the count shows the browser's pace.
What a browser can't tell you
This shows how often the browser draws, which usually equals the refresh rate. It can't read the maximum your monitor supports, its response time, or your input lag. For those, check the monitor's specifications and read input lag explained.
Sources: MDN, requestAnimationFrame; WHATWG, rendering opportunities; Microsoft, Change the refresh rate on your monitor in Windows.