Dead & stuck pixels
Nine pure colors, edge to edge. A dead pixel stays black, a stuck one stays lit.
1 minGuide
Refresh Rate Test
Your real Hz, measured in the browser, plus frame skipping and tearing. 100% in your browser - nothing is uploaded.
30 s2 patterns
Click the preview to run it full screen
Your display
Updates when you move the window to another screen- Resolution
- ---
- device px
- Pixel ratio
- ---
- devicePixelRatio
- Refresh rate
- ---
- measured in this browser
- Color gamut
- ---
- reported by the browser
- HDR
- ---
- standard range
- Orientation
- ---
- current
How to run the refresh rate test
01Pick the right screen
Put this window on the monitor you want to check and close other heavy tabs.
02Read the quick number
The display readout above shows the rate and updates when you move the window.
03Run the full test
Exact Hz, frame time, jitter and missed frames, measured while it runs.
04Check for tearing
Switch to the tearing variant: a sideways split in a moving bar is a torn frame.
What to look for
- A rate that matches the setting in your OS (for example 239.9 to 240.1 for 240 Hz).
- Missed frames staying close to zero. A few during tab switches are normal.
- In a long-exposure photo of the frame row, every cell lit evenly.
What counts as a defect
- A rate lower than the monitor’s setting usually points to settings or the cable, not the panel.
- Constant missed frames mean the system cannot keep up, not that the monitor is faulty.
- Tearing in a browser is rare, because browsers sync to the display; seeing it points to a driver or compositor setting.
What to do next
- Windows: Settings, System, Display, Advanced display, then pick the highest refresh rate.
- Use DisplayPort or an HDMI cable and port rated for the resolution and rate you want.
- On laptops, plug in the charger and turn off battery saver, which often caps the rate.
- Rate is right? See how clean motion looks at it with the ghosting test.
Other screen tests
Each one checks a different part of the panel. The guided check runs them all in order.
Uniformity & clouding
Flat greys and white show clouding, dirty-screen effect and tinted zones.
1 minGuide
Banding & gradients
256 equal steps per ramp. A good panel shows them evenly, a weak one clumps them.
1 minGuide
Sharpness & geometry
One-pixel grids, checkerboards and circles expose scaling blur and bad geometry.
1 minGuide
About the refresh rate test
A 144 or 240 Hz monitor only runs at that rate when the operating system, the cable and the browser all agree. This test times the frames the browser actually paints and turns them into a rate, with jitter and missed frames, so you can see whether you get what you paid for.
It is one of the tests in the Screen & Monitor Test, which also runs a guided check through every test and ends in an inspection reportfor a return or RMA. Every pattern is drawn on your screen's own pixel grid, 100% in your browser - no upload, no install, no account needed.
Frequently Asked Questions
The monitor runs at the rate the operating system sets, which is often 60 Hz by default. Pick the higher rate in the display settings. If it is not offered, the cable or port may not have enough bandwidth for that resolution and rate.
Safari on iPhone and iPad usually paints web pages at up to 60 frames per second even on 120 Hz ProMotion screens, and Low Power Mode caps it too. The panel is fine; the browser is the limit.
Very, on a quiet system: the rate is total time divided by the number of refresh cycles it spans, so it stays exact even though browsers round frame timestamps. The number reflects what the browser paints, so browser and power-saving limits show up as a lower rate.
Safari on iPhone does not allow web pages to go truly full screen. The test fills the whole visible area and hides all controls instead; rotate to landscape, or add the page to your Home Screen, to get the most of the panel in view. iPad and Android support real full screen.
No. Every pattern is drawn locally in your browser, and the inspection report is built and downloaded on your device. Nothing about your screen or your results leaves the browser, and no account is needed.
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