YouTube Shorts accepts vertical 9:16 video up to 60 seconds, with 1080 × 1920 pixels as the recommended resolution, which means any landscape source needs its sides removed, not just any crop, before it can become a Short. The Video Cropper handles that conversion by re-recording exactly the rectangle you specify inside the source frame: pick a browser-decodable video, enter X, Y, width, and height in source pixels, and the tool draws only that region into a Canvas at 30 fps and downloads it as a WebM. Nothing leaves your tab because decoding, cropping, recording, and the Matroska duration fix all run locally on your machine, so the original stays on disk while you calculate the right rectangle. The output keeps the source's full duration, the same region across every frame, and audio only when the browser exposes a capturable track during media capture. Subtitles, chapters, rotation tags, HDR signaling, and most container metadata are not preserved, so plan to verify the downloaded WebM in YouTube's studio preview before deleting the source.
What YouTube Shorts Requires From Your Video
Shorts live inside the YouTube mobile app first, and that shapes three concrete requirements: a vertical 9:16 frame, a duration of 60 seconds or less, and a resolution that survives compression after upload. YouTube accepts 1080 × 1920 as the default recommendation because that resolution matches the phone's native screen and avoids upscaling artifacts. The platform also accepts 720 × 1280 and 1440 × 2560, but anything wider than 9:16 either gets pillarboxed or rejected outright by the Shorts upload path.
The Video Cropper cannot change a source's resolution on its own; it only removes pixels outside a fixed rectangle, so the output dimensions come from the width and height you enter, not from a separate resize step. If your source is taller than the 1080 × 1920 target, you decide whether to keep the full height and just narrow the sides, or to crop a 1080-wide center rectangle that still hits 1920 vertical pixels.
For sources shorter than 60 seconds, the crop alone is enough. For longer sources, trim first using the Video Trimmer, or accept that the resulting WebM will be longer than Shorts allow and let YouTube reject it on upload. The Video Cropper never adjusts duration, so trimming is a separate step that runs locally in the same browser.
Source Files the Video Cropper Will and Won't Accept
The cropper enforces explicit safety limits on the input before it does anything, and each limit gates whether the tool can finish your task:
| Limit | Maximum | Why it matters |
|---|---|---|
| File size | 500 MiB | Larger files fail decoding and are rejected before cropping starts. |
| Decoded duration | 5 minutes (300 seconds) | Longer sources fail the duration check and cannot be cropped. |
| Wider source side | 4096 pixels | Above this, the browser cannot decode the frame, so the cropper returns nothing. |
| Output area | 3840 × 2160 pixels | The cropped rectangle must fit inside this envelope, including for 1080 × 1920 Shorts targets. |
Accepted extensions cover the common desktop and phone containers: MP4, WebM, MOV, M4V, and Ogg. The extension only signals container, not codec, so a file that uses an unusual codec inside an MP4 wrapper will still fail to decode because the browser cannot read the frames. When decoding fails, the tool reports the dimension load failure and you get nothing to crop. Processing happens in real time at the source's playback speed, so a one-minute clip takes roughly one minute while the tab stays open; closing or refreshing mid-process discards the recording.
Pick the Right Crop Rectangle for a 9:16 Short
The cropper uses four pixel values measured from the source frame's top-left corner: X (right offset), Y (down offset), width, and height. Every value must be an untrimmed nonnegative whole pixel count, both width and height must be at least two pixels, and the rectangle must stay entirely inside the decoded source. Invalid rectangles fail without shifting, clipping, rounding, or producing a partial file.
To produce a true 9:16 Short from a landscape source, the cropped rectangle has to honor the same 9:16 ratio. For a 3840 × 2160 source, a centered 1080 × 1920 crop uses X = (3840 − 1080) ÷ 2 = 1380 and Y = (2160 − 1920) ÷ 2 = 120. For a 2160 × 3840 portrait source, a centered 1080 × 1920 crop uses X = (2160 − 1080) ÷ 2 = 540 and Y = (3840 − 1920) ÷ 2 = 960. For a 1920 × 1080 landscape source, the source height only allows a 608 × 1080 rectangle (608 ÷ 1080 ≈ 0.563, the closest whole-pixel 9:16 ratio at the available height), so you cannot reach true 1080 × 1920 from this source without first upscaling, and the cropper does not upscale.
| Source dimensions | Crop rectangle | X | Y | Width | Height |
|---|---|---|---|---|---|
| 3840 × 2160 (landscape) | 1080 × 1920 center | 1380 | 120 | 1080 | 1920 |
| 2160 × 3840 (portrait) | 1080 × 1920 center | 540 | 960 | 1080 | 1920 |
| 1920 × 1080 (landscape) | 608 × 1080 center | 656 | 0 | 608 | 1080 |
Verify the arithmetic yourself before entering values: a 3840-wide source minus a 1080-wide crop leaves 2760 unused pixels, and half of 2760 is 1380. A 2160-tall source minus a 1920-tall crop leaves 240 unused pixels, half of which is 120.
Crop a Video for YouTube Shorts in Your Browser
- Open the Video Cropper in a current desktop browser and choose a local MP4, WebM, MOV, M4V, or Ogg file. Wait for the source dimensions to appear in the dimension field before doing anything else.
- Calculate the crop rectangle that fits inside the source. For a true 9:16 Short, use a width-to-height ratio of 9:16 measured in source pixels, centered horizontally if you want the middle of the frame.
- Enter X, Y, width, and height as whole numbers in the source-pixel fields. Leave the values untrimmed (no leading spaces), keep both dimensions at two pixels or more, and confirm X + width and Y + height stay inside the decoded source.
- Select Crop video. The tool will play the source locally, draw only the requested region into a Canvas at 30 fps, and record that Canvas stream as WebM. Keep the tab open and focused during processing because the recording runs at real-time speed.
- When the WebM is ready, download it, then play it back in your media player to confirm duration, crop position, audio, and visual quality. Only delete the source after you have watched the entire output.
- Upload the WebM to YouTube Shorts. YouTube accepts WebM uploads and will re-encode on its end, so the output does not need a separate transcode unless your editor reports a problem.
What the Crop Keeps and What It Drops
The cropper is one rectangle applied to every frame, not a motion tracker, an object remover, or a redactor. It changes the visible frame region for the entire duration and does nothing else. The decoded pixels inside the rectangle are preserved as drawn, audio is appended to the Canvas stream only when the browser exposes a capturable audio track, and the output WebM uses the first browser-reported WebM recorder among VP9, VP8, and generic WebM.
What does not survive: subtitles burned into the source, chapter markers, attachments, rotation tags, HDR signaling, color metadata, and many container features. Streaming MediaRecorder output also tends to omit a finite container duration, so the tool patches in a Matroska Duration value in TimestampScale ticks using the same standards-tested writer shared with the Video Compressor. The output is verified to be nonempty and to decode at the requested dimensions, but the bitrate is bounded only from 180 kbps to 8 Mbps based on cropped pixel area at 30 fps, and fast motion, noise, grain, source codec, and browser encoder all change the final size. Keep the original file until you have reviewed the full output.
Review the WebM Before You Upload
Real-time processing means a one-minute source takes roughly one minute, so plan to keep the tab open during that window. While the tool plays the source during recording, the source audio may be audible because the browser is actively decoding and playing it back to capture the audio track. If that bothers you, mute the tab in advance; the recording itself picks up the audio stream regardless of the tab's mute state.
After the download appears, check four things:
- Duration matches the source's decoded duration, because the cropper does not trim by time.
- Crop position stays inside the rectangle for the entire clip, especially during camera moves that shift the subject.
- Audio plays back correctly when present, and stays in sync with the picture.
- Resolution and aspect ratio match the 9:16 target you planned, because YouTube will reject uploads outside that envelope.
YouTube accepts the WebM directly, so you do not need to re-wrap to MP4 before upload. If the result looks off, adjust X, Y, width, or height and run Crop video again; each new recording replaces the previous output. The Video Cropper page resets its object URLs, timers, recorder tracks, and playback on every exit path, so leaving and returning does not leak resources. For sources longer than 60 seconds, run the Video Trimmer first so the cropped WebM stays inside the Shorts duration cap; you can also pair this with the cut-a-section workflow when you want a specific segment rather than the full timeline.