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 videos to change the aspect ratio of
Select any number of files — processed locally in your browser, never uploaded
Fits each original video inside the new aspect ratio and adds black letterbox/pillarbox bars to fill the rest, rather than cropping or stretching 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