Online Tool Store
Letterbox Tool
Fit a video into a new aspect ratio - square, portrait, or widescreen - with padded bars instead of cropping, rendered and downloadable. Runs entirely in your browser.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
Nothing is uploaded. Output is recorded live as WebM.
No video yet - choose one to fit it into a new aspect ratio.
How the letterbox tool works
- Choose a video and pick a target aspect ratio.
- The tool scales your video down to fit entirely within that ratio, centering it and filling the rest with padded bars.
- Render the video to record the result and download it.
The method
Each frame is drawn onto a canvas sized to the target ratio, scaled by the smaller of the width or height ratio (so the whole frame fits without cropping), and centered - the classic "contain" fit, the opposite of a "cover" crop. The canvas's live video stream is recorded to produce the final file.
FAQ
What does "letterboxing" mean here?
Fitting a video into a different aspect ratio by scaling it down to fit entirely within the new frame and filling the leftover space with padded bars, instead of cropping or stretching the footage.
Why would I need a different aspect ratio?
Platforms like Instagram Stories (9:16), Instagram feed (4:5), or a square post (1:1) expect specific ratios - letterboxing preserves your entire original frame instead of cropping content out.
Can I choose the bar color?
Yes. Black and white are both available, so you can match the bars to your platform's background or your video's overall look.
Is my video uploaded anywhere?
No. The video is decoded and re-composed entirely in your browser using canvas and MediaRecorder - it never leaves your device.
How we compare
| Feature | Online Tool Store | Video editing software | Platform auto-crop |
|---|---|---|---|
| No file upload - runs in your browser | ✓ | ✓ | ✗ |
| Keeps the full original frame | ✓ | ✓ | ✗ (crops) |
| No install required | ✓ | ✗ | ✓ |
For fitting a full video into a new ratio without cropping anything out, Letterbox Tool keeps your entire frame intact.