Horizontal to vertical video, without cropping

What the blurred background is

A landscape video shown on a phone held upright fills only a band across the middle. This tool keeps that band sharp and fills the space above and below it with the same video, scaled up to cover the frame, blurred and darkened a little. The background moves with the video and takes its colors, so the frame looks finished instead of boxed in by black bars.

Behind slides, screen recordings and anything with text, a plain background often reads better, because a blurred copy of text is just smudges. Pick Black, White or Color for that. The preview in the settings panel is drawn by the same code that makes the file, so what you see there is what you get.

Most browsers blur with the canvas filter built into them. Safari on iPhone, iPad and Mac ships that filter switched off (caniuse), so there the tool blurs in its own code instead. In our tests on a laptop, with the filter switched off in Chrome to match Safari, the two looked the same and our own blur took about 40% longer.

Fit or crop: how much of the picture you keep

Cropping a wide video to a tall shape throws away the sides. Fitting keeps everything and makes the picture smaller inside the frame. For a 16:9 video, this is how the two compare:

These are our own calculations. If the action stays in one part of the frame, a crop can work better: the video cropper lets you place a 9:16 box over it, and the box stays where you put it for the whole video. If people, text or scenery reach the edges, or the action moves around, fitting keeps all of it in.

Sizes for Reels, Shorts and Stories

Instagram's Help Center says a reel can have any aspect ratio between 1.91:1 and 9:16 and should be at least 720 pixels, at 30 frames per second or more (Instagram). Every shape here falls inside that range, and both sizes clear the minimum: 9:16 comes out at 1080 x 1920 or 720 x 1280. The tool keeps your video's own frame rate up to 60 frames per second and adds no frames, so a clip filmed at 24 or 25 frames per second stays that way.

Length matters too. Instagram lets a reel run up to 20 minutes but does not recommend reels over 3 minutes to new audiences (Instagram). YouTube says Shorts can be up to 3 minutes long, are uploaded as vertical videos, and can be uploaded at up to 1080p (YouTube Help), so the 1080p setting here is the most a Short can use. For either, open Use only part of the video and keep the best 3 minutes of a longer recording.

Apps also draw their buttons, captions and profile names over vertical video. For Reels ads, which Meta lists at 9:16, it suggests keeping the top 14%, the bottom 35% and 6% on each side free of text and logos (Meta). By our own arithmetic, a 16:9 video fitted into 9:16 sits between about 34% and 66% of the height. It stays clear of the top zone and only grazes the bottom one, so most overlays land on the blurred area instead of your picture; it does run the full width, though, so keep any text of your own away from its left and right edges.

How long it takes, and what happens to quality

Every frame of the new video is drawn and encoded again, which takes far longer than a copy. In our tests on a laptop in Chrome and Edge, a 20 second 1080p video took 8 to 11 seconds and a 60 second one 14 to 25 seconds, depending on what else the laptop was busy with. A phone can take longer. The progress bar shows the time left, and Cancel stops it at any point.

The picture is saved as H.264, which plays on nearly every phone, computer and app. Its bitrate is worked out from your video, never a fixed default: about the same bits for each pixel of real picture as the original, and far fewer for the background, which is soft and easy to compress. A 9:16 frame made from a 1080p video therefore needs about 40% of the original bitrate. The sound is copied as it is when it is AAC or MP3, the usual case, and in most other cases converted to AAC.

A slow-motion clip recorded at 120 or 240 frames per second is saved at 60. Every new file is written without the original's location, date and device details.

Long videos and large files

Nothing is uploaded, so there is no upload cap to hit, whether your video is 500 MB or several GB. The browser reads it from your device a piece at a time instead of loading all of it, and what has to fit is the new video. The panel shows its expected size before you start, and choosing 720p instead of 1080p makes it about half as big.

A new video of up to about 500 MB on a computer, or about 200 MB on a phone or tablet, is built in memory and then downloaded. On a computer, Chrome and Edge write a bigger one straight into a file you pick, so memory never runs short there. Elsewhere the tool warns you first; if a phone runs out, make the video in stretches with Use only part of the video.

Keep the tab open while a long video is made. The tool asks the browser to keep the screen on where it can, so a phone does not lock halfway.

Which videos and browsers work

You can open MP4, MOV, WebM and MKV videos. The tool decodes and encodes them with WebCodecs, the video engine built into the browser: Chrome and Edge from version 94, Samsung Internet from 17 and Firefox on computers from 130 have it. Safari has had the video part since 16.4 and the sound part since version 26 (caniuse, WebKit). Firefox for Android does not have it.

iPhones can record in HEVC, the High Efficiency format (Apple). To redraw an HEVC video the browser has to decode it, and not every browser can: in our tests on a Windows laptop, Chrome could and Edge could not. When that happens the tool says so before anything runs, and the fast cut still works, because it copies the video without decoding it.