OpenShortsVideo aspect ratio converter: 16:9 to 9:16 in your browser
Turn a horizontal video into a vertical 9:16 one for TikTok, Instagram Reels and YouTube Shorts. The conversion runs on your device, so nothing is uploaded.
Is someone talking in it? OpenShorts reframes with face tracking so the speaker stays in the frame, and cuts the long video into clips with subtitles.
Try the clip generatorThe three ways to fill a vertical frame
A 16:9 video is 1.78 times wider than it is tall; a 9:16 frame is 0.56. Something has to give, and each option trades a different thing:
- Blurred background keeps the whole picture, centred, over a blurred and darkened copy of itself. Nothing is cut off, but the video only fills about a third of the screen height. Good for screen recordings, slides and wide shots.
- Crop to fill uses the full screen and keeps a vertical slice of the frame, which you can slide left or right. It cuts away about two thirds of the width, so it only works when the subject stays in one place.
- Black bars is the plain letterbox: the whole picture, with the rest of the screen left black.
The output is 1080x1920 or 720x1280, as MP4 (H.264) in Chrome, Edge and Safari, or WebM in browsers that cannot encode H.264. Audio is kept.
Why it runs in your browser
Your browser already has a hardware video encoder, and the WebCodecs API lets a page use it. So the file is read, re-framed and encoded on your machine and never uploaded: no queue, no watermark, no account. The limits are the ones that keep a browser tab stable: the first 5 minutes of the video and files up to 2 GB. Keep the tab open while it runs.
When a fixed crop is not enough
A fixed crop cannot follow a person who moves, and it cannot show two people talking at the same time. That is what the OpenShorts YouTube to Shorts converter does: it tracks faces with MediaPipe so the speaker stays in the frame, can stack two people talking in a split screen, and cuts the long video into 3 to 15 clips with subtitles.
Common questions
- How do I convert a video to 9:16 for free?
- Choose the file above, pick blurred background, crop or black bars, and click Convert. The video is processed in your browser and you download a 1080x1920 or 720x1280 file. There is no sign-up and no watermark.
- Is my video uploaded anywhere?
- No. The conversion runs on your device with your browser's own video encoder. The file never leaves your computer or phone.
- Why is there a 5 minute limit?
- The finished video is held in the browser's memory until you download it, and long 1080p videos can exhaust a tab. Short-form platforms rarely take more than a few minutes anyway.
- Which browsers work?
- Current versions of Chrome, Edge, Safari and Firefox. The tool needs the WebCodecs API; a browser without it shows a message instead of failing silently.
Sources
- MDN: WebCodecs API, the browser encoder this tool uses.
- Mediabunny, the open source library that reads and writes the video files. Face tracking in the clip generator: the project source at github.com/mutonby/openshorts.