Uwarp

Output is MP4 (H.264 + AAC). First run downloads FFmpeg (~25 MB) once in this browser.

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Resize video online — video resizer

Resize video online free. Change video resolution or aspect ratio (16:9, 9:16, 1:1) for Instagram and TikTok — MP4 output, no server upload.

What is a video resizer?

A video resizer (video resolution changer) changes the pixel dimensions of a clip — for example resize MP4 to 720p or 1080p, or change video aspect ratio to 9:16 / 1:1 for Instagram and TikTok. This free resize video online tool runs in your browser with FFmpeg WebAssembly, so files stay on your device. For shrinking file size without targeting resolution, use the compress video tool.

Video resizer features

Resize videos and change resolution online, privately in the browser.

  • Resize video online

    Upload MP4, MOV, or WebM and download a resized MP4 at 1080p, 720p, 480p, or 360p.

  • Video resolution changer

    Lower or set resolution when platforms, editors, or uploads need a specific height.

  • Video aspect ratio changer

    Switch to 16:9, 9:16, or 1:1 with pad (letterbox) or crop (fill).

  • Resize MP4 for social

    Prepare clips for Instagram Stories / Reels or TikTok-style vertical frames.

  • No server upload

    Resizing runs locally with FFmpeg WebAssembly.

  • Quality control (CRF)

    Tune H.264 quality so you can resize without unnecessary detail loss.

How to resize a video online

Change the size of a video or resize MP4 in three steps.

  1. Upload video

    Drop an MP4, MOV, or WebM file (up to 200 MB).

  2. Pick resolution and aspect

    Choose 1080p–360p, optional 16:9 / 9:16 / 1:1, and pad or crop.

  3. Resize and download

    Click Resize video, then save the MP4.

Great for

Common video resize and resolution-changer scenarios.

  • Instagram and TikTok framing

    Resize video for Instagram or TikTok with 9:16 / 1:1 aspect presets.

  • Resolution targets

    Deliver 720p or 480p when a site or editor asks for a specific resolution.

  • Downscale before share

    Change video resolution so large phone clips fit upload limits more easily.

  • Aspect fixes

    Use pad or crop when you need a standard 16:9 or square export.

Frequently Asked Questions

Quick answers about this tool—open a question to read more.