Free Tool
Video Canvas Extender
Add letterbox or pillarbox padding to change your video's aspect ratio — 1:1 for Instagram, 9:16 for Stories, 16:9 for YouTube, 21:9 for cinematic. Choose any padding color. All processing is in-browser.
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Add letterbox or pillarbox padding to change aspect ratio — 1:1, 9:16, 16:9, 21:9
Target aspect ratio
Drop a video file or click to upload
MP4 · WebM · MOV — padding added in a background worker
Common use cases
1:1 (Square) — required for Instagram feed posts and some social platforms. Adds top/bottom bars to horizontal video.
9:16 (Vertical) — TikTok, Instagram Reels, YouTube Shorts. Adds side bars to horizontal footage.
16:9 (Widescreen) — YouTube, Vimeo, presentations. Adds top/bottom bars to vertical footage.
21:9 (Cinematic) — adds black bars for a wide-screen film look.
Frequently asked questions
Does it crop my video?
No — nothing is cropped. The tool adds padding (blank canvas area) around your video to reach the target aspect ratio. Your video is centered with padding on two sides.
Can I choose any padding color?
Yes. Use the color picker to choose any solid color, or click White or Black for quick access. The color fills all added canvas area uniformly.
What format is the output?
Output is WebM (VP9). To convert to MP4, use the Video Format Converter tool afterwards.
Can I use a custom aspect ratio?
Yes. Select "Custom…" in the ratio buttons and enter any width and height values. For example, 2:1 or 3:2 are valid custom ratios.
Does it affect the audio?
No. The audio track from your source video is preserved exactly in the output.
Why it's different
Canvas padding for any aspect ratio — adds letterbox or pillarbox bars without cropping, no upload, runs entirely in your browser.
100% Private
Everything runs on your device using in-browser AI. Nothing is transmitted to any server — not the file, not metadata, not filenames.
True Alpha Channel
We export straight (non-premultiplied) alpha so transparent PNGs open with a real checkerboard in Photoshop and Figma — no black halos.
Free Forever
No paywall, no watermark, no premium tier. The full-quality AI is free, supported by non-intrusive ads.
Works Offline
Once loaded, the app and AI models cache locally. Process files without an internet connection. Installable as a desktop or mobile app.
Ready to try it?
Free, private, no signup. 1:1, 9:16, 16:9, 21:9 and custom.
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