Refresh Rate Test

Features

• A five-second window, reporting the compositor rate snapped to common steps: 24, 30, 48, 50, 60, 75, 90, 120, 144, 165, 240
• ⚠️ The median interval is used, not the mean, so one stall cannot turn 60 Hz into 30 Hz
• ⚠️ The first second of warm-up samples is dropped, since those frames are not representative
• Frame count, median frame time, worst frame and dropped frames are all reported
• A frame counts as dropped when it exceeds 1.5 times the median — half a frame late is visible
• A three-way verdict: smooth, slightly uneven, dropping frames
• A block moving at constant speed shows smoothness directly: it jumps on a dropped frame rather than gliding
• Everything runs in your browser; no network requests

How to use

1. Keep the window in the foreground, since a background tab is throttled and the numbers mean nothing
2. Press Measure and wait five seconds
3. Watch the moving block while it runs; the number and the look should agree
4. Read the worst frame and the dropped count: a normal median with a very long worst frame means occasional stalls

FAQ

Why is this different from my monitor specification?

Because this is what the browser actually negotiated, while the specification is the panel ceiling. The usual gaps: insufficient cable bandwidth (4K above 60 Hz needs chroma subsampling or a lower rate on HDMI 2.0), a power saving or sync mode on the display, an integrated GPU output limit, and background throttling in the browser. ⚠️ If the window is not in the foreground the measurement is essentially meaningless, because browsers deliberately reduce the frame rate of invisible tabs.

Why the median rather than the mean?

Because the mean is dominated by outliers. Nearly every measurement contains a stall or two (garbage collection, the moment you switched away, another process taking the CPU). One 800 millisecond gap among 200 gaps of 16.7 milliseconds drags the mean below 30 Hz even though the panel is fine, while the median is immune. That is also why the worst frame is reported separately: it is the direct evidence of a stall.

How are dropped frames counted?

A frame is dropped when it takes more than 1.5 times the median frame time. Half a frame late is visible as a hitch, and the threshold deliberately errs on the strict side. ⚠️ It counts drops on this page, so an animation running here is included in the measurement; for a clean number, leave the page alone while measuring.

What is the moving block for?

The number and the impression are two different things. At a steady 60 Hz a block moving at constant speed looks smooth; when frames drop it jumps, because its position is computed from the time phase and a late time means a late position. That is much closer to what you actually notice while scrolling, dragging or playing. A smooth block with an ugly number means occasional stalls; a stuttering block with a normal median means the answer is in the dropped count.