How to use Resize video
- 1
Drop a video
Choose an MP4, MOV, WebM, MKV or AVI clip (free: 500 MB, 10 minutes). A live preview of the new frame appears at once.
- 2
Pick the shape
Choose 9:16 for Reels, TikTok and Shorts, 1:1 or 4:5 for Instagram posts, 16:9 for YouTube, 4:3, or keep the original shape and only change the size.
- 3
Fit or fill
Fit keeps the whole picture over a blurred copy of the video or a solid colour; Fill crops it to cover the frame, and you slide the crop to keep the important part.
- 4
Set the resolution
Auto keeps the original sharpness up to 1080p; 480p, 720p, 1080p, 1440p and 4K presets give the exact pixel size, such as 1080 × 1920.
- 5
Resize and download
Press Resize video to get name-1080x1920.mp4, an H.264 MP4 that every social app accepts.
Limits and Pro
One video at a time, up to 500 MB and 10 minutes, output up to 4K (2160p), no watermark.
Pro takes files of up to 4 GB and up to 10 hours long. See Pro
About Resize video
Resize video re-frames a clip for the screen it will be watched on. Social apps crop or shrink anything that doesn't match their shape: a landscape phone video posted as a Reel ends up as a thin strip, and a vertical one uploaded to YouTube gets black bars. This tool builds a new frame of exactly the size you want and places the picture in it the way you choose.
Fit shrinks the video until all of it is visible and fills the empty space either with a blurred, slightly darkened copy of the same video — the look most creators use for vertical edits of landscape footage — or with a colour you pick. Fill enlarges the picture until it covers the frame and cuts off what sticks out; the position slider decides whether you keep the left, centre or right (or top and bottom) of the shot. Sizes are set by the short side, so 1080p means 1080 × 1920 for 9:16, 1080 × 1350 for 4:5 and 1920 × 1080 for 16:9.
The result is always an MP4 with H.264 video; the hardware encoder aims at about 5.6 Mbit/s for 1080 × 1920 at 30 fps. AAC or MP3 sound is copied untouched; other audio becomes AAC. Every frame is re-encoded, so expect a short wait; enlarging a small video gives a bigger file but no extra detail. The tool doesn't rotate, trim, add text or change the frame rate.
Privacy
Frames are decoded, redrawn on a canvas and encoded inside this browser tab, with your browser's WebCodecs hardware encoder or, when that isn't available, with ffmpeg.wasm in a Web Worker. The video is never uploaded. Only the ffmpeg engine itself (31 MB, from jsDelivr) may be downloaded, and it contains nothing of yours.
Features
Social formats
9:16, 1:1, 4:5, 16:9 and 4:3 frames with exact pixel sizes from 480p to 4K.
Blurred background
Fit the whole shot over a soft, blurred copy of itself, or over a solid colour.
Crop with position
Fill the frame and slide the crop to keep the subject in view.
Live preview
The preview uses the same drawing code as the export, so you see the final frame.