About this tool

This tool estimates your display's effective refresh rate by timing consecutive requestAnimationFrame callbacks — the browser calls that function right before each repaint, so the interval between calls is a reasonable proxy for how often your screen is actually refreshing while the animation runs. A bouncing ball gives you a visual reference for smoothness while the real measurement happens in the timing data behind it.

The detected rate is computed from the median frame interval over a rolling window of the most recent 120 frames, converted to an implied Hz and then snapped to the nearest common refresh rate (60/75/90/120/144/165/240/360Hz) if it falls within about 6% of one — otherwise it's reported as an unbucketed "Other" value rather than forced into the wrong category.

Key features

• Live Current, Average, Minimum, and Maximum FPS, plus per-frame time in milliseconds
• A stability percentage (minimum ÷ average FPS) showing how consistent frame delivery has been, not just the average
• Detected Refresh Rate readout bucketed to the nearest common Hz value once enough samples have accumulated
• Qualitative status band (Excellent / Good / Average / Limited) based on the detected rate
• Start / Stop / Reset controls and a fullscreen mode for the animation area

Why use it

• Confirm a high-refresh-rate monitor or laptop panel is actually running at its rated Hz, not silently falling back to 60Hz
• Check whether a cable, adapter, or display mode change dropped your effective refresh rate
• Get a rough smoothness comparison between two displays without installing anything

Why refresh rate testing matters

A display can be physically capable of 144Hz or 240Hz and still end up running at 60Hz because of a cable that doesn't support the full bandwidth, a display mode that wasn't applied correctly, a GPU driver setting, or an OS default that silently reverted after a driver update. None of that is obvious just by looking at the desktop — the animation still moves, it just doesn't move as smoothly as it should. A quick timing-based check like this one is often the fastest way to notice the mismatch.

Tips for accurate results

• Let the test run for at least 5–10 seconds before trusting the detected Hz value — the first couple of seconds can be noisy while the browser and OS settle into a steady rendering cadence.
• Close other tabs and background apps that compete for GPU/compositor time — heavy background load can drag your measured rate down independent of your display's real capability.
• Make sure the browser window isn't being scaled, moved between displays, or occluded during the test — any of those can interrupt frame delivery.
• If you have a variable refresh rate (G-Sync/FreeSync) display, expect more variation — that's the display working as intended, not a fault.

A quick accuracy note

This is a browser-based approximation, not a certified hardware reading. Operating systems throttle background tabs, browsers batch and vsync frame delivery differently across platforms, and power-saving states can all shift the numbers. Treat the detected Hz as a strong indicator, not a lab-grade measurement — for a definitive number, check your OS display settings or use a dedicated native refresh-rate testing tool.

Frequently asked questions