Find the pattern with the webcam test
Open the webcam test, click Start camera and watch the preview for half a minute.
- Note whether you see horizontal bands moving up or down, the whole picture pulsing, or the image freezing and cutting out.
- Switch off the room lights and face a window, or wait for daylight. See if the flicker stops.
- Switch the lights back on and turn off any monitor or lamp behind or beside you, one at a time.
- Read the resolution under the preview, and note whether it changes when the fault appears.
Reading the result
| What you see | Likely cause | Where to look |
|---|---|---|
| Dark bands rolling steadily through the picture | Lights flickering at mains frequency, out of step with the camera | Anti-flicker setting |
| Flicker stops in daylight | The room lighting is the cause | Anti-flicker setting, lighting |
| Brightness pumps up and down as you move | Auto exposure hunting in low or uneven light | Lighting |
| A screen in the background shows moving stripes | Normal. The camera and the screen refresh at different rates | Move the screen out of frame |
| Picture freezes, goes black or drops to a low resolution | A USB power or data problem | USB checks |
Set the anti-flicker frequency
Mains-powered lights pulse with the electricity supply: 60 times a second in North America and 50 in Europe and most of Asia, Africa and Australia. A camera set for the wrong one shows rolling bands. Many webcams ship set to one value regardless of where they are sold.
- Windows Camera app: open Camera, select the settings cog and find Flicker reduction. Choose 60 Hz or 50 Hz to match your country.
- Webcam software: the maker's app usually has the same choice, labelled Anti-flicker or Power line frequency. This setting is stored in the camera, so it applies in every app.
- Mac: macOS has no system setting for this. Use the webcam maker's app if there is one.
If you are not sure which value is right, try both. The correct one makes the bands stop immediately.
Change the lighting
- Add light on your face. A brighter scene lets the camera use a steadier exposure. A desk lamp bounced off a wall works.
- Stop dimming LED bulbs. Many dimmable LEDs flicker more at low settings. Run them at full brightness or use a different lamp.
- Replace a failing tube. An old fluorescent tube that flickers to the eye will be far worse on camera.
- Avoid a bright window behind you. It forces the exposure to swing as you move.
USB and power checks
- Plug the webcam straight into the computer, not through an unpowered hub or a monitor's USB ports.
- Try a different port, ideally on the back of a desktop.
- If the webcam has a detachable cable, swap it, and avoid long passive extensions.
- Close other apps that might be using the camera, then start the test again.
Other things to rule out
Turn off any background blur or virtual background while you test, because a struggling effect can look like flicker at the edges of your outline. On Windows, open Settings → Bluetooth & devices → Cameras, select the camera and check whether its own brightness and contrast controls have been changed. If the flicker appears in one app only, the app's video settings are the place to look.
Further reference: Official device or browser documentation ↗
Reviewed October 2026 · How we write our guides · Suggest a correction