Resize a video to 1080p, 720p or exact pixel dimensions

How to use the video resizer

1. Drop a video onto the box or click to choose one.
2. Choose a Size: 4K (2160p), 1440p, 1080p, 720p (the default), 480p, 360p, or Custom width × height.
3. For Custom, enter Width in pixels and Height (0 = keep shape). With Keep the aspect ratio (fit inside) ticked, the video is fitted inside the box without distortion.
4. Tick Allow upscaling only if you need a preset larger than the original.
5. Pick an Output format and press Resize video. The summary shows the old and new size, for example 1920×1080 → 1280×720.

What it does and when to use it

Resizing changes how many pixels each frame has. People use it to fit a form or app that rejects videos above a certain resolution, to make a 4K clip easier to edit on an older laptop, to send a lighter file to someone who will only watch it on a phone, or to match several clips to the same size before joining them in the video merger.

The resizer keeps the whole picture. To cut part of the frame away instead, use the video cropper. To reduce the file size with a target in MB, go to the video compressor, and to change the data rate directly, use the video bitrate changer.

How it works

The tool reads the video’s display size, then works out the new size:

• Presets: scale factor = preset ÷ short side of the video, applied to both sides.
• Custom with one number: the other side follows the original shape.
• Custom with both numbers: the video is fitted inside the box when Keep the aspect ratio is ticked, or stretched to it when it is not.

Widths and heights are rounded to even numbers because common encoders need them. Every frame is then decoded, scaled and re-encoded with Mediabunny and your browser’s WebCodecs encoder in a background worker. The sound is kept and nothing is uploaded.

Worked examples

These sizes come from the tool’s own size function.

A 1280×720 clip set to 1080p returns the message “The video is already 1280×720” unless Allow upscaling is ticked, which gives 1920×1080.

Limits and tips

• Allow upscaling applies to custom sizes too. With it unticked, a custom size larger than the clip is scaled down to fit the original (keeping the shape you asked for), so typing a larger width does not enlarge the clip.
• Large sources are slow on phones, and the result is built in memory. Trim long clips first with the video trimmer.
• If your browser has no encoder for MP4 at the size you chose, try WebM or a smaller size.