Refresh Rate Test
Check how many Hz your monitor is really running at — plus a smooth-motion test that catches dropped frames.
Keep this tab focused and in the foreground while measuring — everything runs locally in your browser.
🛸 Motion test
Follow the saucers. On a healthy display + browser they glide smoothly; visible stutters, jumps or double-images mean dropped frames or a low refresh rate. Faster rows make judder easier to spot.
A frame counts as dropped when its gap is ~2× your median frame time — i.e. the browser missed a repaint.
🔬 Precision test
How it works
- One callback per frame. Browsers fire
requestAnimationFrameexactly once per display repaint, so the gaps between callbacks are your display's frame times. - 120 samples, median math. The test times 120 consecutive frames (after a short warm-up) and takes the median gap — the median shrugs off one-off hiccups that would wreck an average.
- Hz = 1000 ÷ median frame time. A 6.94 ms median → 144 Hz; 4.17 ms → 240 Hz.
- Snap + raw. If the result lands within ~2% of a common rate (60 / 75 / 90 / 120 / 144 / 165 / 240 / 360), it snaps to that — but the raw figure (e.g. 239.8) always stays visible below.
Before you trust a low result
- Background tabs are throttled. Browsers slow hidden tabs to 1 fps or less — the test auto-restarts when you come back, but keep it front-and-centre.
- Battery saver / low-power mode can cap browsers at 30–60 fps on laptops and phones. Plug in and re-test.
- Browser frame caps. Some browsers limit repaints (e.g. Safari Low Power Mode, some VMs or remote desktops) below what the panel can do.
- OS display settings. Many 144–240 Hz monitors ship running at 60 Hz. Windows: Settings → System → Display → Advanced display → pick the top refresh rate.
- Multi-monitor: the browser follows the display the window is on — drag the window to the monitor you want to test, then hit Re-test.
FAQ
How many Hz is my monitor?
Open this page and it measures automatically: your browser repaints once per display frame, so timing 120 frames and taking the median gap gives your real refresh rate — 60, 75, 120, 144, 240 Hz and so on. The result appears in a few seconds, no install needed.
Why does the test say 60 Hz when my monitor is 144 Hz?
Most of the time the operating system is actually running the panel at 60 Hz. On Windows, check Settings → System → Display → Advanced display and pick the highest refresh rate. Battery saver, low-power mode, a browser frame cap, or the window sitting on a slower second monitor can also hold the browser at 60 Hz even when the panel supports more.
The raw value shows 143.8 or 239.8 Hz — is that normal?
Yes. Frame timestamps carry sub-millisecond jitter, so the raw computed rate lands slightly off the nominal number. That is why the test snaps to the nearest common rate (60/75/90/120/144/165/240/360) when the measurement is within about 2% of it, while still showing the raw figure.
Does this work with G-Sync or FreeSync (VRR)?
Yes — browsers composite the desktop at the display's configured fixed rate, so you should see the refresh rate set in your OS. Variable refresh mainly kicks in inside full-screen games, not on a normal web page.
Why do I see dropped frames in the motion test?
A frame is flagged as dropped when its gap is roughly twice the typical frame time, meaning the browser missed a repaint. Occasional skips are normal (background tabs, video, system load). Constant skipping means the machine can't keep up — close heavy tabs, plug in a laptop, or lower the resolution.