Using White Screens and Screen Tests on Multiple Monitors
With two or more displays, fullscreen opens on whichever monitor the browser window is on. Once you know that, it is easy to light a video call from a second screen, check every monitor for dead pixels, or compare two displays side by side with the same white.
Move the window to any monitor, then press F to fill that screen.
1First, extend your desktop
To show different things on each screen, the displays must be extended, not mirrored. Mirroring shows the same image everywhere.
Step-by-step checklist
Tick each step as you go.
2Fill one specific monitor
Fullscreen always uses the monitor that holds the browser window.
Step-by-step checklist
Tick each step as you go.
3Run screens on several monitors at once
Each browser window can be fullscreen on its own monitor, so open one window per screen.
Step-by-step checklist
Tick each step as you go.
- On a Mac, keep System Settings > Desktop & Dock > Displays have separate Spaces turned on (the default). Without it, only one display can show a fullscreen window at a time.
- Press Esc in a window to exit its fullscreen without affecting the others.
4Match brightness and color across monitors
Two monitors rarely show exactly the same white. Showing the same white screen on both makes the difference obvious, so you can adjust them to match.
Step-by-step checklist
Tick each step as you go.
- Brightness percentages are not comparable between monitors: 50% on one can be far brighter than 50% on another. Match them by eye, not by the number.
5Using a TV as a second screen
TVs often crop the picture edges (overscan) and sharpen or tint the image, which spoils tests and makes text blurry.
Key guidelines
- Set the TV’s picture size to Just Scan, Screen Fit or 1:1 Pixel Mapping.
- Choose PC or Game mode to turn off extra processing.
- Set the computer to the TV’s native resolution in the display settings.
- Use the Screen Resolution Test to confirm the edges are not cut off.
Frequently asked questions
Why does fullscreen open on the wrong monitor?
Fullscreen uses the monitor the browser window is on. Exit fullscreen, move the window to the monitor you want, and press F again.
Can I show a different color on each monitor?
Yes. Open a separate browser window for each monitor, choose a different color in each, and make each one fullscreen.
Can I use a second monitor as a light for video calls?
Yes. Put the white screen fullscreen on the monitor beside or behind your camera and turn its brightness up. The Zoom Lighting tool lets you warm or cool the light to suit your skin tone.
Ready to test your display now?
Run free browser tests, check for dead pixels, or open any of the 12 color screens.
Related display guides
How to Go Fullscreen in Chrome, Safari, Edge and Firefox on Any Device
Keyboard shortcuts and steps to make any page fill the whole screen in Chrome, Edge, Firefox and Safari on Windows, Mac, Android, iPhone and Chromebook, and how to exit.
How to Turn Screen Brightness All the Way Up on iPhone, Android, Windows and Mac
Step-by-step ways to set full brightness on iPhone, Android, Windows and Mac, plus the hidden settings (power saving, auto-dimming, white point) that keep a screen dim.
Screen Color Test: How to Evaluate Color Accuracy and Balance on Your Monitor
Test your monitor for color tinting, banding, gamma shifts, and contrast balance. Step-by-step screen color testing guide for PC, Mac, and mobile displays.