Change the aspect ratio of any video online for free. Resize video to 9:16 for TikTok, Reels and Shorts, 16:9 for YouTube, or 1:1 for Instagram with solid or blurred background fill. Browser-based, no uploads, no sign-up.
All processing runs entirely in your browser. Your video is never uploaded to a server.
The Video Aspect Ratio Resizer changes the aspect ratio of any video right inside your browser, with no uploads and no sign-up. Load a clip, pick a target ratio — 9:16 for TikTok, Reels and YouTube Shorts, 16:9 for standard YouTube, or 1:1 for Instagram posts — and the tool re-renders the video into that frame on your own device, then hands you a ready-to-publish file.
Aspect ratio is the relationship between a video's width and height, and every social platform enforces its own. A horizontal 16:9 clip uploaded to TikTok or Reels is shrunk into the centre of a vertical 9:16 screen with wasted black bars above and below. A vertical phone video placed on YouTube leaves the sides empty. Matching the ratio to the platform before you publish fills the screen edge to edge, looks professional, and keeps viewers watching instead of scrolling past a tiny, letterboxed video.
This tool gives you two clean ways to fill the new frame. Blurred background fill scales a soft, out-of-focus copy of your video behind the centered original, so the whole frame is covered with no empty black bars and no cropped content — the same polished look streaming services use for vertical clips. Solid color fill drops your video on a flat background of your chosen color, ideal for clean minimal posts and branded content where you want a crisp border rather than a blurred wash.
Choose your target ratio, pick a background fill mode, optionally set a quality preset, and press Resize Video. The tool re-encodes the video in real time using the browser's native Canvas and MediaRecorder engines, shows a live progress bar with an estimated time remaining, and lets you preview and download the resized file. Because every frame is processed locally, your footage never leaves your device — there is no upload queue, no server storage, and no tracking. Use cases include repurposing horizontal footage for Shorts and Reels, fitting widescreen clips into square Instagram posts, and preparing consistent vertical assets for a multi-platform content calendar.
Resizing runs entirely in your browser using the native HTMLMediaElement, Canvas, and MediaRecorder APIs — no WebAssembly download and no server round-trip. When you press Resize, the tool loads your video into an off-screen element and creates a Canvas sized to the target aspect ratio (720×1280 for 9:16, 1280×720 for 16:9, 1080×1080 for 1:1). On every animation frame it composites the source video, scaled to fit inside the canvas and centered, onto the target frame.
For blurred background fill, each frame first draws a scaled-to-cover, heavily blurred copy of the current video frame onto the canvas using the Canvas 2D filter property, then layers the sharp contained video on top — producing the same edge-to-edge blurred backdrop used by streaming platforms. For solid color fill, the canvas is painted with your chosen color before the video is composited. Audio is routed through the Web Audio API so the original soundtrack survives the re-encode, and MediaRecorder encodes the combined stream into a self-contained MP4 or WebM file. Because the work happens on your device, your video is never transmitted to or stored on Convert26 servers.
Output format depends on browser support: Chrome, Edge and Firefox produce WebM (VP9/VP8), while Safari and some Chromium builds produce MP4 (H.264). The tool picks the best container your browser supports automatically. The source video is scaled with a "contain" fit so no content is cropped — everything that was visible stays visible, just centered within the new ratio. Very large or long videos take longer and use more memory, so use a lower quality preset for heavy files.