Your camera worked fine yesterday, then someone asked you to jump on a video call and the preview showed a black square. Or you just upgraded phones and want to confirm the front lens is actually sharp. Open the webcam test in your phone browser and you’ll have an answer in under a minute.
Open the test and allow camera access
Go to the webcam test in Safari, Chrome, or Firefox on your phone. The browser asks for camera permission the first time. Tap Allow.
A live preview appears within a second or two. Anything longer and the browser is still waiting for permission to be confirmed. If you can see yourself, the camera and browser access are both working.
Switch between front and rear camera
Once the feed is live, a Camera dropdown appears near the top. Tap it to toggle between your front (selfie) camera and the rear lens. Both should produce a live image. A camera that shows black in one position but works in the other tells you which lens has the problem.
On iOS the labels read “Front Camera” and “Back Camera.” On Android they vary by brand, but the options follow the same order the OS assigns them.
What the resolution and frame rate actually mean
Below the preview, the test shows the resolution and frame rate the stream is currently delivering. The number shown is the stream output, not your camera’s hardware rating. The browser requests a default stream that often settles at 1280x720 or 1920x1080 even on a camera rated higher. That’s normal.
A very low number like 640x480 in full daylight can point to a browser fallback mode or a competing app holding camera resources in the background. In a normally lit room, frame rate should hold at 30 fps. If it drops to 15 or lower, close background apps and retest. A reading that stays low after that points to the browser settling into a low-power capture mode.
Test in low light
Move to a dim room and watch the preview. Heavy grain across the whole frame is a real signal, though the native camera app will look cleaner because it applies noise reduction the browser stream skips. What matters is whether the feed stays live and the brightness adapts. A camera that freezes or goes black in low light has a hardware problem.
If nothing shows up
A blank screen or a permission error after the page loads means the browser can’t reach the camera. Work through this in order.
On iOS: Safari asks for camera access per site. If you denied it once, go to Settings > Privacy & Security > Camera, find Safari, and set it to Allow. Then reload the page.
On Android: while Chrome has the page open, tap the lock icon in the address bar. Find Camera and set it to Allow. If that option isn’t there, go to Settings > Apps > Chrome > Permissions > Camera and enable it.
If permission is already granted and the preview still shows black, close every other app that might hold the camera: video call apps, QR scanners, photo filters. Phones can only pipe the camera feed to one app at a time.