If your Short has black bars, they are almost certainly inside your video file — because the bars YouTube adds on its own are not black. YouTube's help centre says so in one sentence: "The padding is white by default, and dark gray when Dark theme is turned on."
That single detail splits this problem into two completely different situations with two completely different answers. Nearly every article on this query treats them as one thing, which is why people end up re-exporting a file that was fine, or leaving bars in a file that was not.
What you are actually looking at
There are two ways empty space can end up beside your video, and they come from opposite directions.
1. Padding the player adds. YouTube does not lock the frame to one shape. Its published behaviour: "The YouTube video player automatically adapts to the size of each individual video." And: "The standard aspect ratio for YouTube on a computer is 16:9. If your video has a different aspect ratio, the player will automatically change to the ideal size to match your video and the viewer's device."
For tall video on a desktop browser, that adaptation includes filling the leftover width. YouTube states that for some video and device aspect ratios — it names 9:16 vertical video on computer browsers — "YouTube may add more padding for optimal viewing," and then tells you exactly what colour that padding is: white by default, dark gray in Dark theme. Nothing is wrong with your file when you see this. It is the player fitting a tall picture into a wide window, and it is the reason a vertical video looks framed on a laptop and full-bleed on a phone.
2. Bars you exported into the video. These are pixels. They are part of the picture, they are usually black, and they travel with the file everywhere it goes — into the Shorts feed, into the thumbnail, into any re-upload. YouTube's guidance on this is blunt and appears on two separate pages.
From the resolution and aspect ratio page: "For best results, avoid adding padding or black bars directly to your video. Padding interferes with YouTube's ability to change the player dynamically to your video size and the viewer's device."
From the general upload page: "When you upload and publish your video, YouTube will figure out the best way to display the content. For the best experience, don't add black bars to the sides of your vertical video. Whether the video is vertical, square, or horizontal, the video will fit the screen."
Read those together and the mechanism is clear. Baked-in bars do not just look bad — they actively break the thing that would have handled the fitting for you. The player sizes itself to the shape of your file, so a file padded out to 16:9 is a 16:9 file as far as the player is concerned — which is exactly the interference YouTube describes.
There is a second consequence specific to Shorts. YouTube classifies a video as a Short when it has "a square or vertical aspect ratio up to three minutes in length." A vertical clip padded out to a 16:9 canvas is no longer a vertical file — the picture inside it is tall, but the frame is wide. That can be the difference between landing in the Shorts feed and landing as an ordinary video. If that is your actual symptom, why your video is not showing as a Short covers the classification rule and its cutoff dates in full.
The fastest fix: remove the bars, don't add more
The fix is an export setting, not an upload setting. There is no YouTube-side toggle in the published documentation that strips padding out of a file after the fact.
- Open the project and check the canvas, not the clip. If your sequence or project is set to a 16:9 frame and your footage is vertical, your editor is doing what you asked: fitting a tall clip into a wide frame and filling the rest with black.
- Set the project frame to match the footage. Square or vertical, edge to edge, with the picture reaching all four sides. YouTube's requirement for Shorts is stated as a shape — "square or vertical" — not a specific ratio.
- Re-export with no letterbox or pillarbox option enabled. If your editor offers a "fit" option that boxes the picture in, choose the one that crops or scales to fill instead.
- Keep the output at or below 1080p. YouTube's Shorts documentation states: "You can upload Short videos with a maximum resolution of 1080p." There is no documented upside to handing it a 4K vertical file.
That last step is where a re-export often comes out heavier than three minutes of vertical video needs to be. This runs the re-encode in your browser, so the file never leaves your machine:
Try it right here
Runs in your browser. Your file is not uploaded anywhere.
To be exact about what this does and does not do: it re-encodes and shrinks, it does not crop. The bars have to come out in your editor first, at the canvas step above. Once they are gone, running the export through the vertical video compressor is how you get a sane upload size without touching the shape you just fixed. The rest of the browser-based tools work the same way — local processing, nothing uploaded.
Other causes, in order of likelihood
Bars on the sides of an already-vertical video. Someone padded it deliberately, often to make a preview look "safe." This is the exact case YouTube names: "don't add black bars to the sides of your vertical video." Undo it.
Bars on the top and bottom of a vertical export. This usually means horizontal source footage was dropped into a vertical project. The picture is wide, the canvas is tall, and the editor filled the gap. Cropping in rather than padding out is the fix — you lose the sides of the frame, but you get a file that fills a phone screen.
Bars that only appear on a computer. Watch the same video on a phone before you change anything. If the empty space is white in light theme and dark gray in dark theme, that is the player, exactly as documented, and there is nothing to fix.
Bars that came in with the source clip. Screen recordings and exports from other apps sometimes arrive already letterboxed. Nothing downstream can tell the difference between those pixels and picture, so they have to be cropped out in the editor like any other content.
How to tell it worked
Check the exported file's dimensions before you upload, not after. If the stored resolution is square or taller than it is wide, and the picture touches all four edges when you scrub through it, the bars are gone.
Then check playback in two places: a phone, where a correct vertical file fills the screen, and a desktop browser, where you should still expect padding — white or dark gray — around a tall video. Seeing that padding on desktop after the fix is the expected outcome, not a failed one.
FAQ
Why does my YouTube Short have black bars on the sides? Because they are part of the video file. YouTube's own padding on computer browsers is "white by default, and dark gray when Dark theme is turned on," so black bars point at your export. The usual cause is a vertical clip exported from a 16:9 project.
Does YouTube add black bars to vertical videos? It adds padding, not black bars. YouTube says the player "may add more padding for optimal viewing" for cases like 9:16 vertical video on computer browsers, and that padding is white or dark gray depending on the viewer's theme.
Will removing the black bars make my video a Short? It removes one obstacle. YouTube's rule is that a video with "a square or vertical aspect ratio up to three minutes in length" gets categorised as a Short, and a padded 16:9 file is not a vertical file. Length and the upload-date cutoff still apply.
Can I crop black bars out after uploading to YouTube? The upload and aspect-ratio pages cited here describe no way to change an uploaded video's frame, so check the official documentation before assuming one exists. Fix it in the source and upload again. If you no longer have the source, note that YouTube only lets you download your own uploads "in either 720p or 360p, depending on the video size" — re-cutting from that is a quality loss.
What resolution should I export a Short at? At or below YouTube's stated Shorts ceiling: "a maximum resolution of 1080p." YouTube publishes no minimum and no specific required ratio for Shorts, so match your footage's shape and stay under that ceiling. For the full numbers, see YouTube Shorts video specs.
Is it different on Instagram or TikTok? Each platform documents its own fitting behaviour, so do not assume YouTube's padding rules carry over. Instagram Reels specs covers that side, and the rest of the upload troubleshooting guides cover the common export failures.
Quotes taken from YouTube Help: resolution and aspect ratios, upload videos, three-minute Shorts and get started creating Shorts, checked 16 September 2026. YouTube changes these pages — verify before relying on them.
