Resize Video.

Crop it to the shape you need instead of scaling it into that shape. Stretching happens when a tool forces a 16:9 picture into a 1:1 or 4:5 box by squashing the width, which makes everyone in the shot look narrow, and it is always avoidable. Choose the ratio here and the tool takes the largest rectangle of that shape that fits inside your footage, lets you slide it to whichever part of the frame matters, and re-encodes only that rectangle. The output is a true 1:1 or 4:5 file with the original proportions intact, at the largest size your source can honestly give.

Because something padded your landscape video instead of cropping it. A 16:9 clip is 1.78 times wider than it is tall and a Reel frame is 0.56 times as wide as it is tall, so the two shapes cannot both be satisfied: either the sides of the picture go, or the top and bottom of the frame get filled with something. Most tools fill it with black, because that is the one-line answer, and Instagram then shows your video as a small strip in the middle of a tall dark rectangle. Cropping is the fix, and it is a real choice rather than a default, which is why this tool puts a frame on the picture and lets you decide what stays.

9:16 for anything that plays full screen in a vertical feed: Instagram Reels, TikTok, YouTube Shorts, Facebook Reels, and Snapchat. 1:1 for a square post in the Instagram or Facebook feed and for LinkedIn video, where a square takes more of the screen than a landscape clip while scrolling. 4:5 for an Instagram feed post when you want the tallest thing the feed allows without going to Reels. 16:9 for YouTube proper, for X, and for anything that will be watched on a laptop. If you only make one, make the 9:16: it is the only shape that fills a phone.

Roughly the top tenth, for the status bar and the search row; the bottom quarter, for the username, the caption, and the sound name, with the navigation bar under that; and a strip about a seventh of the width down the right side, from around a third of the way down to around four fifths, which is the profile, like, comment, and share rail. Reels and Shorts are similar with slightly less at the top and slightly more at the bottom. Those are the numbers the overlays here draw, and they are deliberately labelled approximate: the apps redesign constantly and the exact heights change with the phone. Treat them as a keep-out area with a margin, not a pixel guarantee.

The crop itself loses nothing, but the re-encode does. Changing the shape of the picture means the frames have to be decoded, redrawn, and encoded again, and every encode costs a little. This aims high, at about 0.12 bits per pixel at the output size, which for a 9:16 crop of 1080p footage is around 2.4 Mbps, and it will never spend more bits than the source itself carried, so you cannot accidentally inflate a file. In practice one careful pass is invisible on a phone screen. What you actually lose in a crop is picture: the sides you cut off are gone from that export, and that is the trade you are choosing.

You can, and by default it will not. A 9:16 crop of a 1080p landscape clip is only 608 pixels wide, so exporting it at 1080x1920 means stretching every frame by 1.78 times: the file gets three times bigger and not one pixel of detail is added. Instagram and TikTok both re-encode what you upload anyway, and they are perfectly happy with a 608x1080 file. So the default is fit source, and the platform size is a chip you can pick with the upscale factor named next to it, for the times when something downstream insists on the exact dimensions. If you want a genuinely sharp 1080x1920, the answer is a taller crop of higher resolution footage, not an upscale.