Aspect Ratio Video Converter
Fit a Video Into a New Shape Without Cropping
Need to use Aspect Ratio Video Converter right now?
Pads with black bars to preserve the entire original frame, rather than cutting content away.
Drop a video file, or click to browse
Processed locally in your browser — never uploaded
Fits the original video inside the new aspect ratio and adds black letterbox/pillarbox bars to fill the rest, rather than cropping or stretching your content out of proportion.
Features
- Runs entirely in your browser
- Privacy-first — your data is never uploaded
- Real-time, instant results
- 100% free, no sign-up required
- Works on desktop, tablet, and mobile
- No installation needed
Who uses this tool?
About Aspect Ratio Video Converter
Different platforms expect different video shapes — widescreen 16:9 for most video sites, vertical 9:16 for stories and reels, square 1:1 for certain feed formats. A video shot in one aspect ratio doesn't natively fit another without either cropping content away or adding bars to fill the gap. This tool takes the non-destructive route: it fits your entire original video inside the new ratio and fills the remaining space with black letterbox or pillarbox bars.
Four common target ratios are supported — 16:9 widescreen, 9:16 vertical (for reels and stories), 1:1 square, and 4:3 classic — each computed precisely from your video's actual dimensions using FFmpeg's scale and pad filters together in one operation, run through a real FFmpeg build compiled to WebAssembly entirely inside your browser.
Because this pads rather than crops, none of your original visual content is ever lost or cut off — a portrait video fit into a 16:9 widescreen frame will show black bars on the left and right rather than losing the top or bottom of the shot, and vice versa for widescreen content fit into a vertical frame.
This is the opposite trade-off from cropping to fit a new ratio: padding preserves 100% of the original frame but adds visible bars, while cropping fills the frame completely but discards part of the original content — this tool always chooses to preserve content over filling the frame.
How it works
- Upload your video. The file loads into the browser-based FFmpeg engine.
- Choose a target aspect ratio. 16:9, 9:16, 1:1, or 4:3.
- Convert and download. Your content fits inside the new ratio, letterboxed as needed.
Examples
Fitting a widescreen video for a vertical feed
Input
16:9 video, converted to 9:16
Output
the same content centered with black bars left and right