Video Cropper is a free, no-sign-up browser tool that crops one locally selected video to an exact pixel rectangle and produces a downloadable WebM without uploading the source or output to Lizely. Choose a browser-decodable MP4, WebM, MOV, M4V, or Ogg file, wait for its decoded dimensions to appear, and enter X, Y, width, and height in source pixels. The tool then plays and re-records the source in the current tab, drawing only the requested region into a Canvas element.
The crop is a fixed rectangle applied to every frame. X and Y begin at the source frame's top-left corner, so X moves the region right and Y moves it down. Width controls the selected horizontal extent, while height controls its vertical extent. Width and height must each be at least two pixels, and the complete rectangle must remain inside the decoded source on every frame.
Positive files up to 500 MiB are accepted, but their decoded duration must be greater than zero and no longer than five minutes. No source side can exceed 4096 pixels, and the source area cannot exceed 3840 × 2160 pixels. The cropped output has the requested width and height, with a total area no larger than 3840 × 2160 pixels. An accepted file extension does not guarantee decoding because codec support depends on the current browser.
Processing happens in real time rather than through instant cloud conversion. A one-minute source takes about one minute to process, and the tab must remain open. The resulting WebM may use the first browser-supported recorder available among VP9, VP8, and generic WebM, so the finished file should also be tested in its destination player.
Fixed crop versus other video edits
Video Cropper addresses one specific job: removing unwanted outer areas from every frame with an exact in-frame rectangle. The defaults select the full frame. Changing the coordinates changes the visible region, but the output remains the same width and height entered in the crop fields. Nothing automatically follows a person or object as it moves through the scene.
This makes the tool suitable when the unwanted edges remain in the same positions throughout a clip or when a platform requires a known frame size. It is not a trim-by-time tool, so it cannot keep a beginning, middle, or end of the timeline. It also does not resize the selected region, compress a video without cropping, redact information, blur an object, remove a moving subject, or apply a rectangle that changes from frame to frame.
The result is a newly recorded WebM rather than a claim that every original property remains untouched. Review the complete file before replacing the source, especially when its audio, subtitles, orientation, color, or other metadata matter.
Crop a video locally with exact coordinates
- Choose the source video. Select a local MP4, WebM, MOV, M4V, or Ogg file that the current browser can decode. Wait until Video Cropper reports the source dimensions before entering a crop.
- Check the decoded frame size. Use the loaded source width and height as the coordinate boundary. Do not estimate from a preview size or assume that a familiar extension will decode successfully in every browser.
- Enter the four crop values. Type the top-left X offset, top-left Y offset, width, and height in source pixels. Use nonnegative whole-pixel values that keep the complete rectangle inside the frame.
- Start real-time processing. Select Crop video and keep the tab open while the source plays and the selected region is re-recorded. The source may play audibly during this stage.
- Download and inspect the WebM. Download the result, then check its duration, requested dimensions, picture, audio, and compatibility in the application where it will be used. Keep the original until the entire output has been reviewed.
Set the rectangle against the source dimensions
Before processing, check the crop's right and bottom boundaries. The right edge equals X plus width, and the bottom edge equals Y plus height. Both results must fit within the decoded source. Video Cropper rejects an invalid rectangle without shifting it, clipping the coordinates, rounding values, or creating a partial output file.
| Field | Meaning | Requirement |
|---|---|---|
| X | Horizontal offset from the top-left corner | Nonnegative whole pixels; moving right increases X |
| Y | Vertical offset from the top-left corner | Nonnegative whole pixels; moving down increases Y |
| Width | Horizontal extent of the crop | At least 2 pixels and no greater than the remaining source width |
| Height | Vertical extent of the crop | At least 2 pixels and no greater than the remaining source height |
For one concrete example, imagine a 1920 × 1080 source with X set to 120 and Y set to 80. With a width of 960 and a height of 540, the right-edge calculation is 120 + 960 = 1080 pixels, which remains inside the 1920-pixel source width. The bottom-edge calculation is 80 + 540 = 620 pixels, which remains inside the 1080-pixel source height. The requested area is 960 × 540 = 518,400 square pixels, so the rectangle is within the output limit. Any different source dimensions require the same boundary checks against the newly loaded frame.
Confirm the input and output limits
File type alone does not determine whether a job can run. The browser must decode the selected video, and every safety and size limit must be satisfied. A file that passes one requirement can still be rejected if its decoded duration, dimensions, area, or file size exceeds another limit.
| Item | Accepted boundary |
|---|---|
| File types | MP4, WebM, MOV, M4V, or Ogg |
| Input size | Greater than zero and no more than 500 MiB |
| Decoded duration | Greater than zero and no more than five minutes |
| Source dimensions | No side above 4096 pixels |
| Source area | No more than 3840 × 2160 pixels |
| Output area | No more than 3840 × 2160 pixels |
If the browser cannot decode an accepted extension, try a different file or a browser with codec support. Cropping does not repair unsupported video, and changing an extension does not change the underlying codec support available in the current tab.
Keep the tab open during real-time recording
Video Cropper records the Canvas output as WebM in a single browser pass. Its requested video bitrate is derived from the cropped pixel area at 30 frames per second and is bounded from 180 kbps through 8 Mbps. This is a browser recording setting, not a guaranteed target file size or fixed visual quality.
Fast movement, noise, grain, the source codec, and the browser's encoder can all affect the output. The selected pixels are re-recorded through the browser pipeline, so review the file for compression artifacts, dropped frames, synchronization problems, and changes in fine detail. The tool does not promise a particular output size or quality setting.
When media capture exposes an audio track, Video Cropper appends that track to the Canvas stream. Audio support can vary by browser and capture behavior, and the source itself may be audible while real-time processing runs. Verify both sound and picture even when the original file has audio.
Review the WebM before replacing the original
Play the downloaded WebM from beginning to end in its destination player. Confirm that its duration is present, the crop remains correctly positioned, the requested output dimensions are correct, and the audio track plays when expected. Test the actual player that matters because the browser recorder can choose among VP9, VP8, and generic WebM.
After recording, Video Cropper adds finite Matroska duration metadata and requires a nonempty file that decodes at the requested dimensions. That helps ensure the recording result is structurally usable, but it does not replace visual and audio review. A valid file still needs to look right and work in the intended application.
Keep the source until that review is complete. Cropping does not preserve subtitles, chapters, attachments, rotation tags, HDR signaling, color metadata, or every container feature. It changes the visible frame region and creates a new WebM, so retaining the original avoids losing information that the crop intentionally leaves outside the selected rectangle.