How does the resolution probe work?
We loop through a list of standard video modes — 4K, 1440p, 1080p, 720p, 480p, 360p, and common 4:3 sizes — and call getUserMedia with each as an ideal constraint. After each request, we read MediaStreamTrack.getSettings() to see what the browser actually returned, then release the stream. Browsers always negotiate down to the closest supported mode, so the reported width, height and frame rate represent the camera's real capability rather than what it claims on the box.
Why does the browser keep prompting me for camera permission?
The first getUserMedia call triggers the permission prompt. After you allow once, subsequent probes in the same session reuse that grant. If you see repeated prompts, your browser is set to ask every time — click the camera icon in the address bar and choose Always allow for devicecheckonline.com. On Safari and on iOS, permission is per-tab and resets when the tab closes, which is normal. Reload the page and grant again.
My 4K webcam only reports 1080p. What is wrong?
Three common culprits. First, USB bandwidth — uncompressed 4K30 needs USB 3.0 or a camera that ships MJPEG/H.264; plug into a blue (3.0) port directly, not through a hub. Second, the browser may cap MJPEG decoding and request a raw format the camera cannot deliver at 4K. Third, some webcams only expose their highest mode on Windows via the manufacturer's driver — update drivers and restart the browser. Run the probe again after each fix.
What is a good result on this test?
A modern webcam should deliver at least 1080p at 30fps. Premium models reach 1440p or 4K at 30fps, and high-end streaming cameras hit 1080p60. Frame rate matters more than resolution for smooth motion — 720p60 looks better in calls than 1080p15. If multiple resolutions report identical dimensions, your camera is upscaling internally; the real native resolution is the highest one that returns its exact requested values.
How does this compare to the live preview tool?
This page tests every mode in sequence and reports support. The live preview at devicecheckonline.com/webcam/preview opens one mode and shows real-time FPS, codec and exposure under your current lighting. For chroma-key and green-screen evaluation use devicecheckonline.com/webcam/greenscreen. Use this probe first to learn what your camera can do, then preview to confirm what it actually does.