Is Fit to aspect (add bars) free? Is there a watermark?

Yes — Fit to aspect (add bars) is free to use with no sign-up or watermark. Very large files can still be limited by your browser's available memory and processing resources.

Do my files get uploaded to a server?

No. Fit to aspect (add bars) runs entirely in your browser with WebAssembly, so your MP4, MOV, WebM, MKV file never leaves your device and nothing is stored or seen by us.

What can I put in, and what do I get out?

Fit to aspect (add bars) accepts MP4, MOV, WebM, MKV and gives you back a MP4 file. You can also set aspect ratio and bar colour before you run it. Actual codec support depends on what the bundled engine or browser decoder can read.

Can I control the output?

Yes — you can adjust aspect ratio and bar colour, so you decide the balance between file size and quality.

Free tools · Compress & resize

Fit to aspect (add bars)

Fit a whole video inside a new aspect ratio — 9:16 for Reels, 1:1 for feeds, or 16:9 — by adding centred solid bars instead of cropping. Choose black or white bars. Runs in your browser.

Runs entirely in your browser. Your file is never uploaded — no watermark, no account.

Drop a file or click to chooseMP4, MOV, WebM, MKV

Get a better result

Best for: Keeping the complete frame visible inside vertical, square, portrait, or widescreen delivery when cropping would remove important content.
Input → output: Video becomes a fixed 1080-based H.264 MP4 canvas with the source centered and black or white padding around it, plus AAC audio.
Quality tip: Choose the exact destination canvas and a bar colour that suits the artwork. Review small text after enlarging a low-resolution source.
Know before running: The tool adds bars rather than cropping or generating a blurred fill. Smaller footage may be enlarged, and the fixed canvases can increase output dimensions substantially.
Next step: Compress video if the padded output is larger than the delivery allows.

How to use Fit to aspect (add bars)

1
Choose your file. Drop a supported MP4, MOV, WebM, MKV file into the tool, or click to select one. It stays on your device — nothing is uploaded.
2
Pick your settings. Adjust the available options, then press Run. The first processing run loads the browser engine before conversion begins.
3
Download. Review the result, then download the finished file from your browser with no watermark.

Frequently asked questions

Is Fit to aspect (add bars) free? Is there a watermark?: Yes — Fit to aspect (add bars) is free to use with no sign-up or watermark. Very large files can still be limited by your browser's available memory and processing resources.
Do my files get uploaded to a server?: No. Fit to aspect (add bars) runs entirely in your browser with WebAssembly, so your MP4, MOV, WebM, MKV file never leaves your device and nothing is stored or seen by us.
What can I put in, and what do I get out?: Fit to aspect (add bars) accepts MP4, MOV, WebM, MKV and gives you back a MP4 file. You can also set aspect ratio and bar colour before you run it. Actual codec support depends on what the bundled engine or browser decoder can read.
Can I control the output?: Yes — you can adjust aspect ratio and bar colour, so you decide the balance between file size and quality.