How to fix black bars on a 21:9 monitor
You bought an ultrawide monitor for movies, and the first film you play sits in a small box with black bars around it. The bars are not a fault of the monitor. They come from how video is made and delivered, and in a browser you can remove them.
Three kinds of black bars
- Letterbox: bars above and below. The picture is wider than the frame it is shown in, like a 2.39 movie inside a 16:9 video.
- Pillarbox: bars at the left and right. The picture is narrower than the screen, like a 16:9 video on a 21:9 monitor, or a 4:3 clip on any widescreen.
- Windowbox: bars on all four sides. Both happen at once: a wide movie was letterboxed into a 16:9 video, and then that 16:9 video was pillarboxed on your ultrawide. This is the most common case with streaming services and the most wasteful one.
Letterbox bars that are baked into the video file are just black pixels in the picture. Your player cannot know they are not part of the movie, so it keeps them. That is why the full screen button alone never fixes it.
Why 21:9 is not exactly 2.39
21:9 is a marketing name. Taken literally it is 2.33:1, but real panels differ: 2560×1080 is 2.37:1 and 3440×1440 is 2.39:1. Cinema scope is 2.39:1 as well, so a scope movie and a 3440×1440 monitor are practically the same shape. Other common formats are narrower: 2.20 for some large format releases, about 2.00 for many series, 1.85 for many films, 16:9 (1.78) for TV and most online video, and 4:3 (1.33) for older material.
How much of the screen is black
| Video format | 3440×1440 (2.39) | 2560×1080 (2.37) |
|---|---|---|
| 4:3 (1.33) | 44.2% black | 43.8% black |
| 16:9 (1.78) | 25.6% black | 25% black |
| 1.85 inside a 16:9 stream | 28.5% black | 27.9% black |
| 2.00 inside a 16:9 stream | 33.9% black | 33.3% black |
| 2.20 inside a 16:9 stream | 39.9% black | 39.4% black |
| 2.39 inside a 16:9 stream | 44.6% black | 44.2% black |
The wider the movie, the worse it gets when it arrives inside a 16:9 frame, because the baked-in letterbox and the side bars add up. Try your own setup in the black bar calculator.
How UltraFill removes the bars
- Add UltraFill to Google Chrome on Windows or macOS.
- Open any page with a video and go full screen.
- Hover over the top of the video and click the UltraFill button, or press Alt + U (Option + U on a Mac).
- Click Fill the screen or press Alt + Z.
On sites that do not protect their video, such as YouTube, auto bars reads the picture and finds the baked-in bars by itself (Alt + B). On protected services such as Netflix, Prime Video, Disney+ or HBO Max, the browser hides the frames from extensions, so you pick the format by hand from 16:9, 1.85, 2.20, 2.39, 21:9 and 4:3. The Netflix on 21:9 guide shows that case step by step.
Crop, stretch or elastic
Once the baked-in bars are gone, there is still the question of shape. A 2.39 movie fits a 3440×1440 screen with nothing cut. Anything narrower has to be adapted:
- Crop (free) scales the picture until there are no bars and cuts what overflows at the top and bottom. A 2.00 picture keeps 83.7% of its height, a 16:9 video keeps 74.4%.
- Stretch (free) keeps the whole picture and stretches it evenly. Good for landscapes and sport, less good for faces.
- Elastic stretch (PRO) keeps the center natural and stretches mostly the edges. On protected players it uses a gentler, simpler stretch.
If a crop cuts off heads, drag the frame in the panel preview or press Alt + Shift + arrows to move it. More on picking a mode in stretch, crop or elastic.
Honest limits
- A 16:9 or 4:3 video cannot fill a 21:9 screen without cutting or stretching something. UltraFill lets you choose, it cannot invent picture that is not there.
- On protected video, auto bars, denoise, ambient glow and the split before and after view are not available, because they need to read the frames.
- Sound tools on protected services work after one click on the UltraFill icon, or Alt + Shift + U (Option + Shift + U on a Mac).
- UltraFill runs in Google Chrome on Windows and macOS. It does not change apps outside the browser.
Questions
Why do movies have black bars on my 21:9 monitor?
Most streams are 16:9 videos. Wide movies get bars baked in above and below, and the 16:9 video is narrower than your monitor, so the player adds bars at the sides too.
Can I fix it in the monitor settings?
Monitor scaling modes stretch the whole signal, including the baked-in bars and the desktop. They cannot tell where the movie is inside the video, so the bars usually stay.
Does removing the bars lower the quality?
The picture is scaled up a little, as with any zoom. On a 3440×1440 monitor a 2.39 movie from a 16:9 stream goes from 2560 to 3440 pixels wide.
Which format should I pick for a movie?
Try 2.39 for most cinema releases, 2.20 for some large format films and for series made in about 2.00, and 1.85 for flat films. Hold Alt + C to compare with the original view.
Is it free?
Yes. Fill with crop or stretch, auto bars, all formats, zoom and framing are free. Elastic stretch, sound tools and automation are PRO, with a 7-day trial and no card needed.
UltraFill is an independent extension and is not affiliated with YouTube, Netflix, Prime Video, Disney+, HBO Max or any other service mentioned on this page. Service names are used only to describe compatibility.