1:1 · 4:5 · 9:16
Resize a video for Instagram Reels and feed
Instagram crops anything that does not match its expected shapes, usually cutting off the part you cared about. Pick the target format and keep the whole frame.
Files are processed on your device · nothing is uploaded, stored or logged
How it works
Pick your file. The browser reads it straight from disk. There is no upload progress bar, because there is no upload.
The encoder loads once. A WebAssembly build of FFmpeg, around 30 MB, downloads the first time you use the site and stays cached afterwards.
Your processor does the work. Everything happens in this tab, at roughly half of real time on a modern laptop.
Save the result. The finished file is assembled in memory and handed to your downloads folder.
Which format for which placement
Portrait at 4:5 takes up the most screen space in the feed without being cropped, which is why most creators default to it. It is the safest choice for a normal post.
Square at 1:1 is the classic format and still displays cleanly everywhere, though it occupies less of the screen than portrait.
Vertical at 9:16 is what Reels and Stories expect. Anything narrower gets letterboxed by Instagram itself, usually with results nobody chose.
Padded, not cropped
This tool fits your whole video inside the target shape and fills the remainder with black, rather than cutting the edges off. Nothing you filmed disappears. If you would rather crop tightly to fill the frame, that is a compositional decision better made in an editor where you can see what is being lost.
For a target shape that is not one of these three, work out the numbers with the aspect ratio calculator.
Common questions
Why are there black bars?
Because the entire frame is preserved. Cropping would remove part of your footage without asking.
Which format gets the most reach?
Reels at 9:16 currently get the widest distribution, but that reflects Instagram's priorities rather than anything about the file.
Does it change the length?
No. Only the dimensions change.
Do my files get uploaded?
No, everything runs in your browser.