What it means
| Measured Hz | How often the browser can draw a frame — normally equal to your display’s active refresh rate. 60 Hz on a 144 Hz monitor means the OS is set to 60. |
| Frame time | Milliseconds per frame: 16.7 at 60 Hz, 8.3 at 120, 6.9 at 144, 4.2 at 240. |
| Dropped frames | Frames that took more than 1.5× the normal time. A few are fine; many mean the browser or system is busy, or the cable/bandwidth can’t carry the mode. |
Monitor set below its rated Hz?
- Windows 11: Settings › System › Display › Advanced display › Choose a refresh rate.
- macOS: System Settings › Displays › Refresh Rate (hold Option when clicking Scaled to see more modes on some Macs).
- Use the cable the monitor needs: high refresh at 1440p/4K often requires DisplayPort or HDMI 2.1; an old HDMI cable silently limits you to 60 Hz.
- Laptops may drop to 60 Hz on battery (dynamic refresh / battery saver).
Browser limits
Safari and some browsers cap page drawing at 60 Hz even on 120 Hz screens (iPhone ProMotion, some Macs), so a 60 Hz reading there does not prove the display is at 60. Chrome and Edge report the true rate on most systems.
Related tests
Questions, answered
The number jumps around.
Keep the tab in the foreground and let it settle; background tabs and heavy pages lower the rate. Press “Measure again”.
It says 60 Hz but my monitor is 144 Hz.
Check the OS refresh-rate setting and the cable (see above). If the OS says 144 and the browser says 60, the browser is capping — try Chrome.