Is my video uploaded anywhere?

No. The video never leaves your device — resizing runs entirely in your browser using FFmpeg compiled to WebAssembly.

What's the difference between the two fit modes?

"Crop to fill" scales the video up and crops the edges to fill the target frame exactly, with no black bars, but can cut off parts of the picture. "Fit with blurred background" keeps the entire original frame visible, filling the extra space with a blurred, scaled copy of the same video — the popular look you see on Reels and Shorts.

Is there a file size limit?

Yes, 100MB. Browser-based processing is limited by your device's memory — larger files are more likely to run out of memory or take a very long time, especially on phones.

What format is the output?

Always MP4 (H.264 video, AAC audio) — the format YouTube and Instagram both expect.

Video Aspect Ratio Resizer

Resize a video for Instagram Reels, YouTube Shorts, TikTok or YouTube — crop to fill or fit with a blurred background.

Want to combine this with other edits? Try the full Video Editor

Processed 100% in your browser — nothing you enter here is ever uploaded.

Common use cases

Turning a landscape video into a Reel

Shot a 16:9 video but need it vertical for Instagram Reels or YouTube Shorts? Resize to 9:16 with a blurred background so nothing gets cropped out.

Repurposing one video across platforms

Export the same source clip as 16:9 for YouTube, 1:1 for a feed post, and 9:16 for Shorts — without re-editing in a desktop app.

Fitting a square product video into a portrait post

Use the 4:5 Instagram Portrait preset to make a square or landscape video take up more vertical feed real estate.

How to use the Video Resizer

Drop in a video, then pick the platform you're posting to — Reels/Shorts/TikTok (9:16), YouTube (16:9), Instagram Post (1:1) or Instagram Portrait (4:5), or enter a custom width and height.

Choose "Crop to fill" for a clean full-frame result with no black bars, or "Fit with blurred background" to keep the entire original frame visible with a blurred, scaled copy filling the edges.

Click Resize video — everything runs in your browser, so larger videos and the blurred-background mode take longer. Watch the progress bar.

Preview the result, then download it as an MP4 ready to upload.