VRR Flicker Test
Sweep how often frames reach your screen on a gray field, and watch for the brightness flicker some FreeSync/G-Sync displays show. The measured rate is shown; browsers can’t confirm VRR.
This test deliberately changes how often a new frame is sent to your screen, sweeping from every refresh down to every fourth and back — on a 60 Hz screen that is roughly 60 down to 15 frames per second. Sudden changes in that pace are what make some variable-refresh (FreeSync/G-Sync) screens flicker in brightness, and it shows up most on dark gray. The measured rate is shown on the field so you can confirm the pace really is changing. Your browser still can’t set or check your screen’s true refresh rate, so this stays a subjective observation — not confirmation that variable refresh is on, and not a fault measurement.
01How this test works
Display tests draw precise patterns or measure timing right in your browser. Color and pixel tests fill the screen with exact colors so you can inspect the panel; gradient and sharpness tests draw fine detail that reveals banding or scaling problems.
Timing tests, like refresh rate and FPS, watch how often your screen updates. We ignore the first few frames while things settle, then report the typical result along with a confidence level based on how steady the readings are.
Full-screen tests take over the whole screen and hide everything else so nothing distracts from the panel. You can always exit with the Escape key, and animations are toned down if you have asked your system to reduce motion.
02How to use it
- Set your browser zoom to 100% so pixel-level patterns aren’t scaled.
- Start the test; for full-screen tests, use the on-screen or keyboard controls to change patterns.
- Inspect the whole screen carefully from a normal viewing distance.
- For timing tests, keep the tab in the foreground and let the sample finish.
- Press Escape or the exit button to leave full screen when you are done.
03What this test covers
What it detects
- Dead or stuck pixels, and non-uniformity visible as color or brightness patches
- Banding in gradients and loss of detail in near-black or near-white patches
- A browser-observed estimate of refresh rate and rendering frame rate
- Your reported screen resolution, pixel ratio and color depth
What it can’t detect
- Laboratory-grade color accuracy, contrast ratio, or millisecond response time
- The panel’s true bit depth when the OS or browser reports a scaled value
- Whether variable refresh rate (VRR) or scaling is altering the result
04Troubleshooting
| Symptom | What to do |
|---|---|
| Refresh-rate reading fluctuates | Bring the tab to the foreground, disable battery saver, and remember VRR displays vary by design. |
| Patterns look blurry | Set browser zoom to 100% and your OS display scaling to a native value. |
| Full screen won’t start | Some browsers require a direct click and disallow full screen in embedded contexts; try again with a direct interaction. |
| Can’t tell dust from a dead pixel | Clean the screen first, then inspect the same spot across several solid colors. |
05FAQ
Why does my refresh rate reading fluctuate?
Browsers cap frames to the display refresh, and background throttling or variable refresh rate (VRR) can shift the estimate. We show a confidence level to reflect this.
Is this a calibrated color test?
No. It’s a visual inspection aid. True calibration requires a hardware colorimeter.
Can I test on my phone?
Yes, most display tests work on mobile in full-screen mode.
What’s the difference between a dead and stuck pixel?
A dead pixel stays black on every color; a stuck pixel stays lit on one color and sometimes recovers.
Why does resolution look different from what I expect?
Browsers report CSS pixels; multiply by the device pixel ratio for the physical pixel estimate. Browser zoom also changes the reported viewport.
Does the test change my monitor settings?
No. It only displays patterns and reads values your browser already exposes.
Related tests
Marching bars that step one pixel per frame reveal skipped frames as stutter or doubling — best judged with a phone camera photo.
Estimate how many times per second your display updates by sampling animation frames, with confidence and background-tab detection.
Track a moving object at adjustable speeds and backgrounds to inspect motion blur and ghosting. A visual check, not a millisecond measurement.