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GivenTool

Resize a video

Change a video to 1080p, 720p, 480p or a social size (square, 4:5, 9:16) with bars or crop-to-fill.

Resizing a video solves two different problems. Lowering the resolution, from 4K to 1080p or from 1080p to 720p, makes the file much smaller and easier to send, upload or play on older devices. Changing the frame shape, to a square, a 4:5 portrait or a 9:16 vertical, makes a clip fit a social feed without the platform cropping it in a way you did not choose.

Resolution presets set the shorter side of the video, so a vertical phone clip resized to 720p becomes 720 by 1280 rather than being squashed into a landscape frame, and the aspect ratio never changes. By default a video that is already smaller than the preset is left at its size, because enlarging adds pixels but no detail. Social presets produce an exact frame: fit inside with black or white bars when nothing may be cut off, or fill the frame and trim the edges when a full-bleed look matters more. Custom sizes accept any width and height; leave one at 0 to keep the proportions.

The output is an MP4 with H.264 video and AAC audio, which every platform accepts. Scaling uses the Lanczos filter for sharp results, dimensions are kept even as H.264 requires, and the work happens on your device with FFmpeg in WebAssembly. Encoding runs at roughly real time for 720p on a typical laptop. Need a specific region rather than a whole-frame resize? Use Crop video.

How to use it

  1. Drop a video (MP4, MOV, WebM, MKV, AVI, 3GP).
  2. Choose a resolution such as 720p, or a social size such as 9:16 vertical.
  3. For a different shape, choose bars or crop-to-fill; for custom sizes, type the width and/or height.
  4. Click Resize and download the MP4 when the progress bar finishes.

Frequently asked questions

Does 720p mean 1280 × 720?

For a landscape video, yes. For a vertical video it means 720 × 1280: the preset sets the shorter side so the orientation is kept.

Should I use bars or crop to fill?

Bars keep the whole picture but leave empty space. Crop to fill uses the whole frame but trims the sides or top and bottom, so keep the subject centred. For precise control over what is kept, use Crop video.

Will a smaller resolution reduce the file size?

Usually a lot: 1080p to 720p typically cuts the size by half or more. For a hard size limit such as 25 MB, use the video compressor, which targets a size directly.

Can I make a video bigger, for example 720p to 1080p?

Turn off "Never enlarge a smaller video". The frame will be 1080p, but it will not contain more detail than the original.

Which formats come out?

Always MP4 (H.264 + AAC). To get WebM, MOV or another format, run the result through the video converter.

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