--- title: "Video Aspect Ratio Changer - Crop or Pad | CanDoYa" description: "Change video aspect ratio to 16:9, 9:16, 1:1, 4:5, 4:3, or 21:9. Crop or add bars locally, then download a watermark-free MP4." url: https://candoya.com/tools/video-aspect-ratio-changer/ locale: en type: browser-tool --- # Video Aspect Ratio Changer Category: Social & Creator ## What is a video aspect ratio changer? A video aspect ratio changer reframes a clip for a different screen shape, such as 16:9 landscape, 9:16 vertical, or 1:1 square. Choose crop to fill the frame or padding to keep every part of the picture. The conversion runs locally in your browser and keeps the first audio track. Changing frame shape requires a trade-off. **Crop to fill** preserves natural proportions but removes equal areas from the center-facing edges. Fit with bars preserves the whole picture, scales it inside the target frame, and fills unused space with your chosen color. The browser loads FFmpeg WebAssembly only when you export. It uses Lanczos scaling, square pixels, H.264 video, AAC audio, and fast-start MP4 output. Your source file is not uploaded. Conservative limits are 100 MB on mobile or low-memory devices, 250 MB on a typical desktop, and 500 MB on high-memory desktops. ## How to use it 1. **Choose a video** - Drop a common video file into the tool or load the generated sample clip. 2. **Pick a target ratio** - Choose 16:9, 9:16, 1:1, 4:5, 4:3, 21:9, or enter custom even dimensions. 3. **Choose crop or padding** - Crop for an edge-to-edge frame, or fit with bars to preserve the whole picture. 4. **Process and download** - Start the local conversion, preview the MP4, and download it without a watermark. ## Who it's for - **Short-form creators** can turn a landscape clip into a 9:16 frame for Reels, TikTok, or YouTube Shorts. - **Social teams** can make 1:1 square and 4:5 portrait exports without sending campaign footage to a server. - **Video archivists** can place 4:3 footage inside a 16:9 frame without stretching faces or cutting the original image. - **Presenters** can convert recordings to a standard widescreen or cinematic frame before sharing them. ## Expert note Converting 16:9 landscape to 9:16 vertical with a centered crop retains only about 32 percent of the source frame area. If a face, caption, or product sits near an edge, use padding or crop the source in a dedicated editor with a movable focal point. ## Frequently asked questions ### Is my video uploaded when I change its aspect ratio? No. Your browser reads the source and creates the output locally with a WebAssembly video engine. The engine code downloads on first use, but the selected video and finished MP4 are not uploaded to CanDoYa or stored in an account. ### Is this aspect ratio changer free and watermark-free? Yes. You can choose a ratio, preview the framing, process the clip, and download the result without an account, subscription, credits, or watermark. Practical limits come from your device's available memory and processing speed. ### How large a video can I process? The conservative limit is 100 MB on mobile or lower-memory devices, 250 MB on a typical desktop, and 500 MB on high-memory desktops. Files near those limits can still take several minutes because video must be decoded, scaled, and encoded frame by frame. ### What is the difference between crop and padding? Crop enlarges the source until it covers the target frame, then removes the excess from opposite edges. Padding scales the whole source inside the frame and fills unused space with a color. Both preserve natural proportions; neither stretches faces or objects. ### How do I change a 16:9 video to 9:16? Choose the 9:16 preset. Crop to fill creates an edge-to-edge vertical frame but removes much of the left and right sides. Fit with bars preserves the full landscape image and adds space above and below it. Preview both before exporting. ### Will the result keep its audio? Yes, when the source contains a readable audio stream. The tool encodes the first audio track as AAC alongside H.264 video. Silent sources remain silent. Extra audio tracks, subtitles, chapters, attachments, and source metadata are not copied. ### Does changing aspect ratio reduce video quality? The video must be decoded and encoded again, so some generational loss is unavoidable. The tool uses high-quality Lanczos scaling and a balanced H.264 quality setting. Avoid repeated conversions and avoid upscaling a small source when possible. ## Related tools - [Crop Video](https://candoya.com/tools/crop-video/) - [Video Resizer](https://candoya.com/tools/video-resizer/) - [Vertical Clip Cropper](https://candoya.com/tools/vertical-clip-cropper/) - [Video Converter](https://candoya.com/tools/video-converter/) - [Video Compressor](https://candoya.com/tools/video-compressor/) --- *Markdown edition of , published for AI agents and other automated readers. Index of key pages: .*