Change Video Aspect Ratio
Free online tool to change any video's aspect ratio — 16:9 for YouTube, 9:16 for TikTok / Reels, 1:1 square for Instagram feed, 4:3 retro, or any custom ratio. Three methods: stretch (anamorphic-style), crop (zoom + frame), or letterbox (black bars). Runs in your browser via FFmpeg WebAssembly — no upload, no watermark, no sign-up.
Drop files here or click to browse
Max 10240.0 MB per file · drop multiple for batch
or press Ctrl+V to paste
100% private — files never leave your device
·Free — no sign up, no watermark
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How to Use Change Video Aspect Ratio
- Drop your video onto the aspect ratio changer
- Pick the target aspect ratio — 16:9, 9:16, 1:1, 4:3, or set custom width × height
- Choose method: Stretch (fastest), Crop (no distortion), or Letterbox (adds bars)
- Click Process and download — full-resolution MP4 with audio intact
Features
- Change to any aspect ratio — 16:9 (YouTube), 9:16 (TikTok / Reels / Shorts), 1:1 (Instagram), 4:3 (retro / TV), 21:9 (cinematic), or any custom ratio
- Three methods on one tool — stretch (fastest, distorts), crop (zoom in, no distortion), letterbox (black bars, no distortion, no crop)
- Live preview before processing — see exactly how the new ratio looks
- Runs in your browser via FFmpeg WebAssembly — your video never uploads to a server
- MP4, MOV, MKV, WebM all supported; audio preserved on every method
- Free with no watermark, no sign-up, no file size cap below plan limit
Frequently Asked Questions
- How do I change a video's aspect ratio online?
- Drop your video into the aspect ratio changer, pick a target ratio (16:9 for YouTube, 9:16 for TikTok, 1:1 for Instagram square), choose method (stretch / crop / letterbox), click Process. Runs in your browser — no upload to a server.
- What's the difference between stretch, crop, and letterbox?
- Stretch distorts the video to fit the new ratio (fastest, no quality loss but people / faces look pinched). Crop zooms in and cuts off the edges (no distortion, but you lose some of the frame). Letterbox keeps the original frame and adds black bars on the sides or top/bottom (no distortion, no crop, just bars). Pick stretch for graphics-only content; crop for narrative video; letterbox for archives.
- How do I convert horizontal video to vertical for TikTok / Reels?
- Use 9:16 target. For a 16:9 source, the cleanest method is crop (zooms the center) — see our vertical conversion tool. Stretch will make people look very tall; letterbox will leave large black bars at top/bottom.
- How do I convert 4:3 to 16:9 widescreen?
- Use our dedicated 4:3 to 16:9 tool — pre-configured with the right stretch factor for old SD content.
- Will changing aspect ratio reduce video quality?
- Stretch and letterbox are near-lossless (only video container is re-encoded). Crop loses the cropped region but keeps the rest at full quality. No method adds compression noise — output uses high-quality H.264.
- Is this aspect ratio changer free, no sign-up?
- Yes — fully free, no watermark, no sign-up, no file size cap below your plan limit. Runs in your browser via FFmpeg WebAssembly so we have zero server costs to pass on.