Resize a Video
Pick a video and a target size — it's scaled in your browser (aspect ratio preserved), nothing is uploaded.
Resize a video
Pick a video and set a target width and/or height. Leave one blank and the aspect ratio is preserved (the missing side is computed automatically, and always to an even number so the encoder is happy). It re-encodes in your browser with ffmpeg; nothing is uploaded.
Notes
- Give both width and height to force an exact size, or just one to scale proportionally.
- The output is re-encoded as H.264: an mp4, mov, m4v, or mkv keeps its container; other inputs (webm, …) come out as MP4.
- Downscaling shrinks the file; upscaling won't add real detail.
FAQ
Is my video uploaded?
No — ffmpeg runs in your browser tab; the file never leaves your device.
Why did my height change when I only set width?
To keep the aspect ratio — the other dimension is computed for you.
What codec and quality does the resized video use?
The video stream is re-encoded with H.264 (libx264) at CRF 23 with the medium
preset — a sensible quality/size balance that plays everywhere. An mp4, mov,
m4v, or mkv keeps its container; other inputs (webm, …) are converted to MP4,
since those containers can't hold H.264/AAC.
Why did my requested size get nudged by one pixel?
H.264 with the standard yuv420p pixel format requires even width and height. When a dimension is computed automatically it is always rounded to an even number, so a request like width 641 can come out as 640×360 rather than failing in the encoder.
Developer & Automation Access
Run it from the terminal
Same engine as this page, headless — via the gizza CLI:
gizza tool video-resize 'url=https://example.com/input' 'width=1280'New to the CLI? Get gizza →
Open it by URL
Pre-fill and auto-run this tool with query parameters — the names match the API/CLI:
https://gizza.ai/tools/video-resize/?url=https://example.com/input&width=1280Machine-readable descriptor: tool.json — title + parameters JSON Schema for agents.