Cropping a video is one of those operations that sounds laughably simple until you actually try to do it for free. You open the first search result, drop your file in, wait two minutes for the upload, click crop, and then a watermark appears in the corner of the preview with a paywall behind it. You try the next result. It uploads, processes, downloads, and the output is 480p when your input was 1080p. The third one wants you to sign up. The fourth caps you at 100 MB.

This is the dominant pattern in the free-video-tools space. The economics are simple: server-side conversion costs money, advertising barely covers it, so the business model has to come from somewhere. That somewhere is usually a watermark, an upscale to a paid tier, or a quality cap that pushes you toward the paid tier. None of that has anything to do with what cropping a video actually requires, which is a four-number rectangle, an FFmpeg filter, and a few seconds of CPU.

TL;DR

  • Use Clipy's crop video tool. Drag a box on the preview, click crop, download. No watermark, no signup, no upload — the crop runs in your browser using WebAssembly FFmpeg.
  • Output keeps the input's resolution within the crop rectangle, the original codec, and the original bitrate envelope. No silent downscale to 480p.
  • If your goal is changing aspect ratio (16:9 to 9:16 for TikTok, or 1:1 for Instagram), the aspect ratio converter is the better tool — it handles the math for you with letterbox, fill, or crop modes.
  • If you actually want to resize (scale) rather than crop, use resize video instead.
  • FFmpeg one-liner if you want to do it on the command line: ffmpeg -i in.mp4 -vf "crop=W:H:X:Y" -c:a copy out.mp4

Crop vs resize vs aspect ratio change — three different operations

The terminology trips people up because most tools use them interchangeably. They are not.

Crop keeps a rectangular region of the original frame and throws everything else away. The pixels inside the rectangle stay exactly as they were. A 1920x1080 video cropped to a 1280x720 region in the middle is still genuinely 1280x720 of the original sharp pixels.

Resize (scale) keeps the whole frame and changes its dimensions. A 1920x1080 video resized to 1280x720 has every original pixel resampled into a smaller grid. You lose detail.

Aspect ratio change changes the shape of the frame from, say, 16:9 to 9:16, which requires deciding what to do with the parts that don't fit: letterbox (black bars), fill (blurred background of the same content), or crop (cut off the edges that don't fit).

If you're cutting off the corner of a screen recording where you accidentally captured your menu bar, you want crop. If you're shrinking a 4K file because your editor can't handle 4K, you want resize. If you're reformatting a horizontal video for Instagram Reels, you want an aspect ratio change.

The math behind a crop rectangle

FFmpeg's crop filter takes four numbers: width, height, x-offset, y-offset. The x and y are measured from the top-left corner of the original frame. Width and height are the size of the rectangle you're keeping. So crop=1280:720:320:180 means "keep a 1280x720 rectangle starting 320 pixels from the left edge and 180 pixels from the top."

Two gotchas. First, for H.264 video in yuv420p (which is everything you'll encounter in 2026 unless you're working with ProRes), both width and height of the cropped rectangle must be divisible by 2. If they're not, the encoder will either error out or silently round, depending on the encoder version. Most browser-based tools handle this rounding for you; the Clipy tool does. If you're on the command line, use crop=trunc(W/2)*2:trunc(H/2)*2:X:Y to round down to the nearest even number.

Second, the x and y offsets must put the rectangle entirely inside the original frame. crop=1280:720:1000:500 applied to a 1920x1080 video means the rectangle stretches from x=1000 to x=2280, which is beyond the right edge. FFmpeg will error, but with a confusing message. Visual crop tools save you from this; the Clipy crop tool only lets you draw rectangles that are inside the frame.

Why most "free" croppers either watermark or upcharge

The structural problem with free server-side video tools is that you, the user, are uploading megabytes or gigabytes of data to someone's S3 bucket. They're paying for the storage, the egress, and the CPU to process the file. Even with cheap cloud pricing, that adds up fast at scale. Display advertising on a niche tool page barely covers the bandwidth.

So the watermark exists for a reason: it's a soft upsell. The tool works, the output is fine, but a small logo in the corner says "upgrade to remove." The upgrade prices vary but are rarely worth it for a single crop. The other common pattern is a quality cap — your 1080p input becomes 720p or 480p in the output unless you upgrade. Sometimes this is disclosed; often it is not, and you only notice when the file you download looks worse than what you started with.

The third pattern is the file size cap. Free tier caps at 100 MB, sometimes 200 MB. For a 4K screen recording, 200 MB is about 90 seconds of footage. So you trim, you compress, you fight the limits, and eventually you either pay or give up.

The browser-local approach sidesteps all of this. There's no S3 bucket because the file never uploads. There's no egress cost because the CPU work happens on your machine. There's no bandwidth bill, so there's no reason to put a watermark on the output. Clipy's crop video tool is genuinely free in the only way that matters: free of watermark, free of upload, free of file size limit, free of account requirement, free of quality degradation.

How to pick the crop rectangle

Most people drawing a crop rectangle have one of a few common goals. Knowing which one you have makes the choice easier.

Cutting out a menu bar or taskbar from a screen recording. Crop a strip off the top or bottom equal to the height of the bar. On macOS the menu bar is usually 24–28 pixels at the standard scaling; on Windows the taskbar is 40–48 pixels.

Removing a webcam overlay you don't want. If the webcam was in a corner, crop that corner out. Be aware this changes the aspect ratio — see the next section.

Zooming in on a region of interest. Crop tightly around the region. The output will be that region at the original pixel density, which is usually higher than if you'd zoomed in post-hoc on the full frame.

Squaring a horizontal video. Pick a square in the middle of the frame. Or use the aspect ratio converter which has a 1:1 preset.

Aspect ratio after cropping — the part that breaks Twitter previews

When you crop, the output aspect ratio is whatever shape you drew. If you cropped a 16:9 video into a 4:3 rectangle, the output is 4:3. This is usually fine for the immediate use case but can break downstream embeds.

Twitter's inline player expects 16:9, 1:1, or 9:16. Anything else gets letterboxed in the preview. Instagram Feed wants 1:1 or 4:5. Reels and TikTok want 9:16. YouTube accepts everything but the thumbnail preview math assumes 16:9.

If your destination is a specific platform, plan the crop to match its aspect ratio. Or do a crop-then-convert flow: crop to remove the unwanted region, then use the aspect ratio converter to fit the result into the target aspect with letterbox or fill.

The codec question — will my output still be playable?

When you crop a video, the encoder has to write a new file because the frame dimensions changed. You can't crop without re-encoding. (Well, you can, with very specific tricks involving cropping metadata, but no consumer tool does this and most players ignore the metadata.)

This means cropping is always a transcode. The Clipy crop tool re-encodes with H.264 in yuv420p, faststart enabled, and a CRF that preserves quality without bloating the file. Output is playable in every browser, in QuickTime, in VLC, in every social platform's upload validator, and in every embed surface.

The audio is stream-copied (-c:a copy) because cropping doesn't touch audio, so there's no quality loss there.

If your input file is in an unusual container (MKV, WebM, MOV) and you want the output in MP4, the crop tool produces MP4 by default. If you need a different format, convert after cropping with the relevant tool — MKV to MP4, WebM to MP4, MOV to MP4, etc.

What happens to file size after cropping

Cropping shrinks the frame, which means fewer pixels per frame to encode, which means the output file is smaller than the input. Roughly proportional to the area ratio. A crop that cuts 25% of the area off makes the file roughly 25% smaller. Not exactly, because video compression is content-dependent, but in the ballpark.

If the output is still bigger than you want for sharing, run it through the video compressor. If you want to drop the resolution as well as crop, do the crop first and then the resize.

The command line version, for power users

If you'd rather skip the browser entirely:

ffmpeg -i input.mp4 \
  -vf "crop=1280:720:320:180" \
  -c:v libx264 -crf 20 -pix_fmt yuv420p \
  -c:a copy \
  -movflags +faststart \
  output.mp4

Substitute your actual crop rectangle in the crop=W:H:X:Y filter. CRF 20 is a high-quality preset; raise it to 23 for smaller files, lower it to 18 if you're going to re-encode again later and want headroom.

To preview the crop rectangle before committing, FFmpeg has -vf cropdetect which scans the video and prints the largest non-black rectangle (useful for auto-removing letterbox bars). For interactive picking, the browser tool is faster.

The summary path

Open Clipy's crop video tool. Drag a box on the preview to define your rectangle. Click crop. Download. The whole thing happens in your browser, the output has no watermark, the resolution is whatever your crop rectangle is in original pixels, and the file is never uploaded.

For aspect ratio changes use aspect ratio converter. For scaling down to a smaller resolution use resize video. For shrinking the file size after cropping use video compressor. Each one runs the same way: in your browser, no upload, no signup, no watermark.