Crop a video
Choose an MP4 or MOV, drag the box over the part of the picture you want to keep (or type the pixels), and download a new MP4 that shows only that part. Presets give you square, vertical 9:16, wide 16:9, 4:5 and 4:3. Everything runs in your browser.
Checking what your browser can do…
How it works
- •Choose or drop a video. A frame from it appears with a crop box on top.
- •Drag the box to move it and its corners or edges to resize it, with a mouse or a finger. Pick a shape to lock the proportions, or type the left, top, width and height in pixels. Move the slider to check the box against other moments of the video.
- •Press Crop video. Every frame is redrawn to the box and re-encoded as H.264; the sound is copied without re-encoding.
- •Download the new MP4. A phone video that was stored sideways with a rotation flag comes out upright.
- •The file is read with mp4box.js and written with mp4-muxer, two open-source libraries served from this site (licences: /tools/vendor/NOTICE-media.txt). Decoding and encoding use your browser's own WebCodecs; nothing is sent anywhere.
What it does and what it cannot do
- •Reads MP4, MOV and M4V up to 1 GB with H.264 video (HEVC from phones only where your browser can decode it). WebM, MKV and AVI are not supported.
- •Needs a browser with WebCodecs and an H.264 encoder: recent Chrome or Edge on a computer, Safari 16.4 or later, or Firefox 130 or later. The page checks first and says so if yours cannot.
- •The picture is re-encoded at a bitrate scaled to the cropped size, so a little quality is lost, as with any crop.
- •Widths and heights are rounded down to even numbers, because H.264 needs that. The crop box is the same for the whole video; it does not follow moving things.
- •The output is never enlarged: a small crop gives a small video.
- •Date, location and other metadata are not copied. HDR video is not tone-mapped.
Questions
- Is my video uploaded?
- No. Your browser reads, crops and saves the video itself; nothing is sent anywhere.
- How do I crop a video to a square or 9:16 for Instagram or TikTok?
- Pick Square 1:1 or Vertical 9:16 under Shape. The box takes that shape; drag it over the part you want and press Crop video.
- Does it work on a phone?
- The crop box works with touch. Whether your phone's browser can encode video depends on the browser: the page checks and tells you. Recent Safari on iPhone and Chrome on Android usually can, but long videos are slow on a phone.
- Does cropping lose quality?
- A little: every frame is re-encoded. The bitrate is scaled to the size of the crop so the result looks close to the original.
- Can I make the cropped video bigger again?
- No. Cropping keeps the original pixels of that area. Scaling it up would only make it blurrier, so the page does not do it.
- Is the sound kept?
- Yes, copied without re-encoding when it is AAC, which almost all MP4 and MOV files use.