You've finished editing your video, you open Instagram to post it, and… the framing is completely off. The sides are cropped, or there are ugly black bars everywhere. Sound familiar? The problem is almost always the wrong resolution or aspect ratio.
Every social media platform has its own preferred video dimensions. If your video doesn't match, the platform will auto-crop or letterbox it — often cutting off important content. The fix is straightforward: resize your video to the right dimensions before uploading. And you can do it for free, right in your browser, with a tool like VideoTools Video Resizer.
Video Size Requirements for Each Platform
Here's a quick reference table for the major platforms. Bookmark this — you'll come back to it.
| Platform | Orientation | Resolution | Aspect Ratio | |----------|------------|-----------|--------------| | TikTok | Vertical | 1080×1920 | 9:16 | | Instagram Reels | Vertical | 1080×1920 | 9:16 | | Instagram Feed (Square) | Square | 1080×1080 | 1:1 | | Instagram Feed (Landscape) | Landscape | 1080×566 | 1.91:1 | | YouTube | Landscape | 1920×1080 | 16:9 | | YouTube Shorts | Vertical | 1080×1920 | 9:16 | | X (Twitter) | Landscape | 1280×720 | 16:9 | | LinkedIn | Landscape | 1920×1080 | 16:9 |
Notice a pattern? Vertical short-form content (TikTok, Reels, Shorts) all use 1080×1920. Landscape content (YouTube, LinkedIn, X) uses 1920×1080 or 1280×720. If you know which format you're targeting, resizing becomes simple.
What Happens If You Upload the Wrong Size?
Automatic cropping. Platforms like Instagram will crop your video to fit their display format. If your subject isn't perfectly centered, important elements — text, faces, product shots — can get cut off. You won't see this until after the video is live.
Black bars. If the aspect ratio doesn't match, many platforms add black letterbox or pillarbox bars to fill the frame. This makes your content look unprofessional and takes up valuable screen space that should be showing your video.
Blurry playback. Uploading a video that's too small (say, 480p to a platform expecting 1080p) means the platform upscales it, resulting in a soft, blurry image. Always start with the highest resolution you have and resize down — never up.
How to Resize a Video Online (Step by Step)
You don't need to install any software. Here's how to resize a video using VideoTools:
Step 1: Open the Video Resizer. Go to the VideoTools Resize tool in your browser. No account or download needed.
Step 2: Drop your video file. Drag and drop your video onto the upload area, or click to select a file. The tool supports MP4, MOV, WebM, AVI, and MKV. Your file stays on your device — nothing is uploaded to any server.
Step 3: Select your target size. Pick a platform preset (like "TikTok / Reels / Shorts" for 1080×1920) or switch to Custom mode and enter exact pixel dimensions. The presets handle the math for you.
Step 4: Choose Fit or Fill mode. This determines how your video fits the new frame. More on this below.
Step 5: Click Resize and download. Hit "Start Resize" and wait a few seconds. Once processing is done, download your resized video as an MP4.
That's it. Five steps, no watermark, no sign-up.
Fit vs. Fill — Which Should You Use?
This is the most important decision when resizing, and it depends entirely on your content.
Fit (Letterbox) keeps your entire video visible. If the aspect ratios don't match, black bars are added to fill the remaining space. This is the safe choice — you never lose any content. Use Fit when your video contains important text, UI elements, or graphics near the edges. It's also better for tutorials and screencasts where every pixel matters.
Fill (Crop) scales your video to completely fill the target frame, cropping the edges if needed. The result looks cleaner — no black bars — but some content at the edges will be cut off. Use Fill when your subject is centered, like a person talking to camera or a product in the middle of the frame. It's the more visually appealing option for most social media posts.
When in doubt, try both. The tool is free and processes quickly, so you can compare the results in seconds.
Tips for Better Results
Shoot at the highest resolution possible. Resizing works best when you're scaling down. Going from 4K to 1080p looks great. Going from 480p to 1080p looks terrible. Always start with the best source material you have.
Keep the subject centered when changing orientation. If you're converting a landscape video (16:9) to vertical (9:16) using Fill mode, whatever is in the center of the frame is what survives the crop. Plan your shots accordingly, or use Fit mode to keep everything visible.
Resize first, then compress if needed. Resizing changes the dimensions but may increase file size if the output resolution requires re-encoding. If your file is too large for the platform's upload limit, run it through a video compressor after resizing. For more on file size limits, see our guide on compressing videos for TikTok.
Match the platform's native aspect ratio. Don't just resize — make sure the aspect ratio matches too. A 1920×1080 video displayed on TikTok (which expects 9:16) will be heavily cropped or letterboxed regardless of its resolution.
Alternative Methods
If you prefer command-line tools, FFmpeg can resize videos with a single command:
ffmpeg -i input.mp4 -vf "scale=1080:1920:force_original_aspect_ratio=decrease,pad=1080:1920:(ow-iw)/2:(oh-ih)/2:black" -c:a copy output.mp4
This is essentially what VideoTools does under the hood, but wrapped in a simple drag-and-drop interface. If you're comfortable with the terminal, FFmpeg gives you maximum control.
FAQ
Can I resize a video without losing quality? Downsizing (making a video smaller) preserves quality well — you're discarding pixels, not creating them. Upsizing (making a small video larger) will reduce sharpness because no new pixel data is generated. For best results, always resize from a higher resolution source.
How do I resize a video for Instagram Stories? Use 1080×1920 pixels with a 9:16 vertical aspect ratio. This is the same size used by TikTok, Instagram Reels, and YouTube Shorts, so one resize covers all of them.
What if my video is horizontal and I need vertical? You have two options: Fill mode crops the sides to fill a vertical frame (best when the subject is centered), or Fit mode adds black bars on top and bottom to keep all content visible. For the best result, re-shoot in vertical orientation if possible.
Do I need to install software to resize a video? No. VideoTools runs entirely in your browser using WebAssembly technology. There's no software to download, no account to create, and no watermark on the output.