How do I crop a video without uploading it?

Open it here. Your browser reads the file and decodes the frames, each frame is cut down to the box on this page, and your browser's own WebCodecs codecs encode the result, which is handed back as a download. Nothing is sent to a server, and there is no account.

How do I crop a landscape video to 9:16?

Choose 9:16. On a 1920 x 1080 clip that places the largest centred tall box, 608 x 1080 at x 656; drag it sideways to keep the subject in it, then crop. The output is exactly 608 x 1080: the crop is not scaled up to a bigger size.

Why is my phone video sideways, and which way do the crop numbers go?

Phones often store video sideways with a rotation flag that players follow. This page reads the flag and shows the picture as it plays, so the box and its numbers are in display pixels: a clip stored 1920 x 1080 with a 90 degree flag is cropped as a 1080 x 1920 frame. Turn adds 90, 180 or 270 degrees on top of that, and the box is drawn on the turned picture.

Why are the width and height always even numbers?

H.264 stores colour at half resolution, so browser encoders need an even width and height. A size you type or drag is rounded down to an even number, and the side a ratio sets goes to the nearest even number, so a preset can be a pixel off: 16:9 across a 1080 wide frame is 1080 x 608, not 1080 x 607.5.

What happens if the crop box goes past the edge of the video?

A dragged box stops at the edge. A typed one is moved back inside and the stage says where to, so x 1500 with a width of 1080 on a 1920 wide frame becomes x 840. A typed box bigger than the frame is shrunk to fit, and a width or height of 0, or anything under 16 px, is refused rather than encoded.

Does cropping a video lower its quality?

The picture has to be re-encoded, because the cropped frames are new frames, so some quality can be lost. It is encoded at a high quality setting: a fixed quality level where your browser's encoder offers one, otherwise a bitrate scaled to the crop's pixel count. The sound is copied untouched when the format can hold it (AAC or MP3 in an MP4, Opus or Vorbis in a WebM) and it does not start before the file's zero point; otherwise it is re-encoded at 128 kbps, and if your browser cannot decode it the page says so and offers Remove sound.

Does the cropped video stay in sync?

The finished file is read back and measured. Its picture length is compared with the original's, and where its sound starts against the picture is compared with the original, each against one frame (33.3 ms at 30 fps). The result says whether both are within one frame, or by how much they missed.

Which formats can it open and save, and how big can the video be?

It reads MP4, MOV, WebM, MKV and MPEG-TS, as long as your browser can decode the video inside, and writes MP4 with H.264 or WebM with VP9 (VP8 where VP9 is missing). Before anything is encoded it asks your browser whether it can write that codec at the crop's size, and says so if not. Videos up to 250 MB and 10 minutes are cropped in one go: a bigger file is refused before it is read, and a longer one as soon as its length is known.

Video Cropper

Open a video, draw the box you want to keep and download the cropped copy, made in this browser tab. The box is measured in display pixels, the picture as it plays, so a phone clip stored sideways with a rotation flag is cropped the way you see it. The 4:5, 1:1, 9:16 and 16:9 presets place the largest centred box of that shape; a box typed past an edge is moved back and the move is stated, and both sides are kept even for H.264. The finished file is read back before it is offered: its picture size must match the box, and its length and where its sound starts are measured against the original.

Open a video to crop

· or drop one anywhere on the stage

Never uploadedNo accountUp to 250 MBUp to 10 minutes

Crop: x

Position: xy

Aspect: 4:5

Duration: none yet

Turn

Format

Sound

Download

Ready. Choose a video, or drop one on the stage.

1920 x 1080, centre square1:1, centred
1080 x 1080 at x 420, y 0
Crop past the right edgex 1500, w 1080 on a 1920 x 1080 frame
moved back to x 840 and flagged; a 0 px width is refused, never encoded
Duration and audio sync24.000 s at 30 fps, AAC audio
measured on the finished file against one frame, 33.3 ms; a bigger gap is stated with the result

The box is in display pixels: the picture as it plays, after the file's own rotation flag and any turn chosen here. Drag the box to move it, drag a corner or an empty part of the frame to draw a new one, or type the numbers under the stage; with the keyboard, the arrow keys move the box and Shift with an arrow resizes it. Width and height are kept to even numbers, because H.264 needs them: a size you type or drag is rounded down, and the side a ratio sets goes to the nearest even number, so a preset ratio can be a pixel off. A dragged box stops at the edges and never gets smaller than 16 px on a side. A typed box that runs past an edge is moved back inside, one bigger than the frame is shrunk to it, and one under 16 px on a side is refused, and the stage says which happened. Sound is copied as it is when the format can hold it (AAC or MP3 in an MP4, Opus or Vorbis in a WebM) and it does not start before the zero point of the file; otherwise it is re-encoded at 128 kbps, and sound that needs re-encoding but that this browser cannot decode is refused with a way round it. When the work ends, the file is read back: its container, codecs and picture size must match the plan or it is not offered, and its length and where its sound starts are measured, not predicted.

Accuracy. Crop numbers are display pixels, counted after the video's own rotation flag and any turn you add, and the box is always kept inside the frame with even sides. Cropping re-encodes the picture, so some quality can be lost, and the finished file is read back to measure its length and where its sound starts against the source, with any gap over one frame stated. Which codecs can be read and written depends on your browser, an unsupported one is refused before encoding, and videos up to 250 MB and 10 minutes are cropped on your device and never uploaded.

The encoding is done by your browser, and the file handling by one open source library served from this site. Containers are read and written by Mediabunny 1.55.7 under the MPL-2.0 (licence text, the exact package, source), bundled unmodified. Video and sound are decoded and encoded by the WebCodecs codecs built into your browser, which is why the formats on offer depend on it.

Common questions

How do I crop a video without uploading it?: Open it here. Your browser reads the file and decodes the frames, each frame is cut down to the box on this page, and your browser's own WebCodecs codecs encode the result, which is handed back as a download. Nothing is sent to a server, and there is no account.
How do I crop a landscape video to 9:16?: Choose 9:16. On a 1920 x 1080 clip that places the largest centred tall box, 608 x 1080 at x 656; drag it sideways to keep the subject in it, then crop. The output is exactly 608 x 1080: the crop is not scaled up to a bigger size.
Why is my phone video sideways, and which way do the crop numbers go?: Phones often store video sideways with a rotation flag that players follow. This page reads the flag and shows the picture as it plays, so the box and its numbers are in display pixels: a clip stored 1920 x 1080 with a 90 degree flag is cropped as a 1080 x 1920 frame. Turn adds 90, 180 or 270 degrees on top of that, and the box is drawn on the turned picture.
Why are the width and height always even numbers?: H.264 stores colour at half resolution, so browser encoders need an even width and height. A size you type or drag is rounded down to an even number, and the side a ratio sets goes to the nearest even number, so a preset can be a pixel off: 16:9 across a 1080 wide frame is 1080 x 608, not 1080 x 607.5.
What happens if the crop box goes past the edge of the video?: A dragged box stops at the edge. A typed one is moved back inside and the stage says where to, so x 1500 with a width of 1080 on a 1920 wide frame becomes x 840. A typed box bigger than the frame is shrunk to fit, and a width or height of 0, or anything under 16 px, is refused rather than encoded.
Does cropping a video lower its quality?: The picture has to be re-encoded, because the cropped frames are new frames, so some quality can be lost. It is encoded at a high quality setting: a fixed quality level where your browser's encoder offers one, otherwise a bitrate scaled to the crop's pixel count. The sound is copied untouched when the format can hold it (AAC or MP3 in an MP4, Opus or Vorbis in a WebM) and it does not start before the file's zero point; otherwise it is re-encoded at 128 kbps, and if your browser cannot decode it the page says so and offers Remove sound.
Does the cropped video stay in sync?: The finished file is read back and measured. Its picture length is compared with the original's, and where its sound starts against the picture is compared with the original, each against one frame (33.3 ms at 30 fps). The result says whether both are within one frame, or by how much they missed.
Which formats can it open and save, and how big can the video be?: It reads MP4, MOV, WebM, MKV and MPEG-TS, as long as your browser can decode the video inside, and writes MP4 with H.264 or WebM with VP9 (VP8 where VP9 is missing). Before anything is encoded it asks your browser whether it can write that codec at the crop's size, and says so if not. Videos up to 250 MB and 10 minutes are cropped in one go: a bigger file is refused before it is read, and a longer one as soon as its length is known.

Crop numbers are display pixels, counted after the video's own rotation flag and any turn you add, and the box is always kept inside the frame with even sides. Cropping re-encodes the picture, so some quality can be lost, and the finished file is read back to measure its length and where its sound starts against the source, with any gap over one frame stated. Which codecs can be read and written depends on your browser, an unsupported one is refused before encoding, and videos up to 250 MB and 10 minutes are cropped on your device and never uploaded.