Free tool · H.264 · Runs in your browser
Crop a video precisely
Short answer
Set the width, height and X/Y offset of the box you want to keep, and the tool cuts that rectangle out of every frame and re-encodes it. On our 1920 × 1080 test clip a 608 × 1080 box for 9:16 kept 31.7% of the frame and made a 1.32 MB file; a 1080 × 1080 box for 1:1 kept 56.3% and made 1.86 MB. Nothing is uploaded.
Choose a video to begin.
The preview and processor use the same selected file. Invalid boxes are rejected. Odd dimensions and offsets round down to the even 4:2:0 grid shown above; there is no subject detection.
Key takeaways
- Cropping removes pixels; it does not squeeze the picture. A 608 × 1080 box from a 1920 × 1080 frame keeps 31.7% of the area, and a 1080 × 1080 box keeps 56.3%.
- Output size follows the box: 1.32 MB for the 9:16 crop and 1.86 MB for the 1:1 crop, against 13.53 MB for the original.
- Quality against the same region of the source: SSIM 0.9815 and 0.9822. Both crops were re-encoded as H.264 at the encoder default quality with AAC audio.
- H.264 with 4:2:0 color needs even numbers, so odd widths, heights and offsets are changed and the tool says so. Asked for 607 × 1079 at 655, 1, it used 606 × 1078 at 654, 0.
- A box that runs off the frame is pulled back inside it: 800 px wide at x 1500 became x 1120, with a note shown instead of a failed run.
What the tool does to your file
You choose the box yourself. There is no face or action detection: the rectangle stays where you put it for the whole clip. The tool checks the numbers against the real size of the video first, then runs one ffmpeg crop with your four values.
| Setting | Value | What it means |
|---|---|---|
| Crop | crop=width:height:x:y | A fixed rectangle, the same in every frame |
| Video | H.264 (libx264), yuv420p, preset veryfast | Re-encoded once at the encoder default quality (CRF 23) |
| Audio | AAC | Re-encoded |
| Whole pixels | X, Y, width and height are integers | Anything else is rejected with a message |
| Even values | Rounded down to even numbers | H.264 with 4:2:0 color requires them |
Measured: two crops of a 1080p clip
Measured on a 10 second 1920 × 1080 excerpt of Big Buck Bunny (CC BY 3.0, Blender Foundation) with a speech soundtrack. It is an animated film, not camera footage, so the sizes of camera video will differ. The tool's own ffmpeg arguments ran on the same single-thread WebAssembly engine your browser downloads; times are from a headless run and your device will differ.
SSIM compares each output with the same rectangle cut from the source; 1.0 would be identical.
| Crop | Box (width × height at x, y) | Share of the frame kept | Output | Output size | SSIM | Time |
|---|---|---|---|---|---|---|
| 9:16 center | 608 × 1080 at 656, 0 | 31.7% | 608 × 1080 | 1,317,398 bytes (1.32 MB) | 0.9815 | 16.6 s |
| 1:1 center | 1080 × 1080 at 420, 0 | 56.3% | 1080 × 1080 | 1,855,388 bytes (1.86 MB) | 0.9822 | 23.8 s |
The Crop a video tool on a 10 second 1080p clip, 13.53 MB as published.
When your numbers do not fit
A crop that starts outside the frame, runs past its edge or uses odd values would make ffmpeg fail or produce a different crop from the one you asked for. The tool corrects the box and shows what it changed. These are two real requests and what the tool did with them:
| You asked for | The tool used | What it told you |
|---|---|---|
| 607 × 1079 at 655, 1 | 606 × 1078 at 654, 0 | Rounded to 606×1078 - H.264 requires even dimensions. X/Y rounded down to 654/0 for the 4:2:0 pixel grid. |
| 800 × 1080 at 1500, 0 | 800 × 1080 at 1120, 0 | X offset moved to 1120 so the crop box stays inside the frame. |
The tool's own correction of a crop box, 1920 × 1080 source.
Picking a box for a vertical or square post
A landscape 1920 × 1080 frame is 16:9. A 9:16 box that keeps the full 1080 pixel height is 608 pixels wide (1080 × 9 / 16 = 607.5, rounded to the even number 608), which is 31.7% of the picture, so the subject has to fit in a column under a third of the frame. A 1:1 box is 1080 pixels wide and keeps 56.3%.
The box can sit anywhere. We centered both (x 656 and x 420); if your subject is off center, move X. The live preview in the tool shows the box before you run it.
Free tools:Crop video to 9:16Trim by timestampCompress a videoSocial media image sizes
Crop or resize
Cropping throws away the edges and keeps the pixels inside the box at full detail. Resizing keeps the whole picture and changes its dimensions. If you only want a smaller file, use the compress tool; if you want a different shape without losing the edges, add bars instead of cropping.
Questions people ask
How do I crop a video to 9:16?
For a 1920 × 1080 clip, use a box 608 × 1080 and set X to move it sideways. Our test crop kept 31.7% of the frame.
Does cropping lower the quality?
The cropped region is re-encoded once: SSIM 0.9815 and 0.9822 on our two test crops. The pixels inside the box are not scaled.
Why did the tool change my numbers?
H.264 with 4:2:0 color needs even widths, heights and offsets, and a box cannot leave the frame. The tool adjusts the box and shows each change.
Why did the file get so much smaller?
Re-encoding at the encoder default quality produced about 1,054 kbps for the 9:16 crop, against 10,827 kbps for the source. A source that is already lightly compressed would not shrink so much.
Can the box follow a face or move during the clip?
No. The box is fixed. Nothing here detects subjects or tracks them.
Is the audio kept?
Yes, re-encoded as AAC. A video with no audio crops normally.
Is anything uploaded?
No. Files up to 100 MB are processed in your browser.
Related
Sources and how we checked
- FFmpeg Filters Documentation (read 2026-10-06)
- FFmpeg wiki: Encode/H.264 (CRF and presets) (read 2026-10-06)
Reviewed October 9, 2026. The measurements ran the tool’s own ffmpeg arguments on the same single-thread WebAssembly engine your browser downloads. The script, the results and the saved documentation are in data/seo/hub/evidence/2026-10-09/tools.