Refresh Rate Test

You paid for a 120, 144 or 240 Hz display — but is it actually running that fast right now? Operating systems ship new monitors at 60 Hz by default, cables silently limit bandwidth, and battery savers cap frame rates without telling you. This test measures the real rate by timestamping every animation frame the browser draws.

The method is direct: browsers fire one requestAnimationFrame callback per display refresh, so the interval between callbacks is the length of one frame. The big number is the median of the last 60 intervals — steady against outliers — while the graph draws each individual frame time, and any frame that takes over 1.5× the median is highlighted and added to the skipped-frame counter.

The moving strips below the readout turn numbers into something your eyes can judge: three objects travel at the same speed, but one updates every frame, one every second frame and one every fourth. The difference you see between the lanes is exactly the difference between owning a high-refresh display and running it at a fraction of its rate. A speed slider lets you make the comparison harsher or gentler.

One honest limitation: this measures what this browser tab receives, not what the panel's specification sheet says. Low-power modes, background throttling, heavy pages in other tabs and some browsers (Safari in particular) can cap animation frames below the display's ability. If the number reads low, close other tabs and check your OS display settings and cable before blaming the monitor.