To get rid of black bars and make standard 16:9 videos fill your entire screen, the fastest way to achieve true fullscreen on an ultrawide monitor is to install a dedicated browser extension like UltraWide Video or UltraWideo. These tools let you zoom or stretch any online video to match your monitor's 21:9 or 32:9 aspect ratio with a single click, turning a letterboxed video into an immersive, edge-to-edge experience.
Why videos don't play in fullscreen on an ultrawide monitor
Most online videos are produced in a 16:9 aspect ratio, which results in black bars on the sides when viewed fullscreen on an ultrawide monitor (e.g., 21:9 or 32:9). This mismatch is the core issue: your screen is wider than the video's native frame, so the player leaves empty space on the left and right. Additionally, many films and shows, especially cinematic content (e.g., 2.39:1 CinemaScope), are often encoded within a 16:9 frame by streaming services, leading to black bars on all four sides of an ultrawide display. This "windowboxing" happens because the streaming platform adds black bars top and bottom to the cinematic footage, then wraps that entire 16:9 image inside your ultrawide screen, leaving even more empty space.
The best browser extensions for fullscreen on an ultrawide monitor
Browser extensions are the primary and most effective solution for viewing online videos in fullscreen on an ultrawide monitor without black bars. Two verified, reliable options are UltraWide Video and UltraWideo. Both work on Chrome, Firefox, and Edge, and they give you precise control over how the video fills your screen.
After installation, reload the video tab, this is crucial, as the extension needs to re-scan the page to take effect. Once reloaded, click the extension icon in your browser's toolbar to open its control panel.
For basic usage, simply click the extension icon while a video is playing, then select a display mode like "Zoom" or "Upscale" (depending on the extension). This instantly crops the top and bottom of the video to match your ultrawide width, eliminating side black bars. If you prefer a more automated approach, some extensions let you set a global rule so every video automatically fills the screen when you enter fullscreen mode.
How to use zoom, stretch, and keyboard shortcuts
Once the extension is installed, you'll typically have three main modes. The "Zoom" (or "Upscale") mode proportionally enlarges the video, cropping the top and bottom to fill the width, this is the recommended option for most content because it preserves the original aspect ratio and simply cuts off a small portion of the frame. The "Stretch" mode widens the video horizontally to fill the screen without cropping, but this distorts the image, making people look wider and objects appear stretched. Use this only if you don't mind the distortion or if the video's composition makes cropping unacceptable.
For quick adjustments, most extensions support keyboard shortcuts. On Windows, press Ctrl+↑ to zoom in and Ctrl+↓ to zoom out. On Mac, use ⌘⇧↑ and ⌘⇧↓. These shortcuts let you fine-tune the zoom level without opening the extension panel, which is especially handy when you're already in fullscreen mode and want to nudge the video to the perfect size.
Fine-tuning your fullscreen experience
To get the most out of your extension, explore its advanced settings. Many extensions offer an "Apply only in fullscreen" toggle, this ensures the video scaling only activates when you enter fullscreen mode, leaving the browsing experience untouched when you're not watching. This is a great feature if you want to keep YouTube's normal layout while scrolling but get the immersive fill when you hit the fullscreen button.
You'll also find preset aspect ratios like 21:9 or 32:9, which are perfect if your monitor has a specific ultrawide resolution. If you need more precision, use the fine-grained scale slider to adjust the zoom by 1% increments. This is useful for content that has unusual letterboxing or when you want to crop out just a tiny bit more from the top or bottom.
Regarding quality, while zooming or upscaling videos to fill an ultrawide screen, the loss in picture quality is generally minimal and often unnoticeable, especially when viewing 1080p or 4K content on a 1440p ultrawide monitor. The video is simply being enlarged to fit, and modern upscaling algorithms do a good job of keeping edges sharp. You won't see pixelation unless you're starting with very low-resolution footage.
Fullscreen playback in desktop video players
If you're watching local video files, browser extensions won't help, but VLC Media Player has a built-in solution. Open your video in VLC, press F for fullscreen, then right-click on the video and go to Video → Crop. From there, select a crop ratio that matches your monitor (e.g., 21:9 or 32:9). This will crop the top and bottom of the video to fill your screen, just like the browser extensions do. You can also use the keyboard shortcut C to cycle through crop presets quickly. This works for any local file, whether it's a movie rip, a downloaded YouTube video, or a home video. If VLC's fullscreen toggle isn't responding, you may need to go full screen on Windows 10 first to resolve system-level focus issues.
For a quick reference, here's a summary of the key differences between the two main approaches:
- Browser extensions (UltraWide Video / UltraWideo): Best for streaming services like YouTube, Netflix, and Disney+. They offer zoom, stretch, keyboard shortcuts, and fullscreen-only toggles.
- VLC's crop function: Best for local files. It's a manual crop, but it's reliable and doesn't require any additional software.
Regardless of which method you choose, the result is the same: your video fills the entire ultrawide screen, and you can finally enjoy that cinematic immersion without any black bars. Whether you want to use an ultrawide monitor with a Mac (just use the ⌘ shortcuts instead of Ctrl), get YouTube videos to play on an ultrawide monitor (install UltraWide Video and hit Ctrl+↑), watch Netflix on an ultrawide monitor (enable the extension and select "Apply only in fullscreen"), or get Disney+ to play in fullscreen on an ultrawide monitor (the same extension works, just reload the tab after installing), these tools have you covered.
For the wider topic, see use an ultrawide monitor with a mac.
