Free Video Crop

Worked example

Add a 1920×1080 clip called clip.mp4. "Mode" starts on "Crop to fill", "Aspect ratio" on 9:16 (labelled "TikTok / Reels") and "Quality" on "Balanced". Under the preview the tool shows "1920×1080 → 606×1080", and a highlighted box marks the part that will be kept. Drag the box sideways, or move "Horizontal position" away from its starting 50%, then press "Crop video". The bar counts "Cropping… 40%", and when it ends the page says "Cropped video ready" with the new file size and a player. The download is named clip_crop_9x16.mp4. Now choose "Fit (no cropping)" instead. The box disappears, a second preview shows the whole picture on a blurred copy of itself, the size line changes to "1920×1080 → 1080×1920" and the button reads "Make 9:16 video". The download becomes clip_fit_9x16.mp4.

Which settings to use, and the limits

• Choose "Crop to fill" or "Fit (no cropping)" first. "Crop to fill" keeps a box of the chosen shape and throws the rest away. "Fit (no cropping)" keeps the whole picture, scales it into the new shape and fills the empty space under "Background" with "Blurred video", "Colour" (a colour picker that starts on white) or "Black". "Free" is offered only when cropping, and it keeps the video's own shape, so use it with "Crop size" to zoom in. If you switch to Fit while "Free" is chosen, the tool moves to 9:16.
• Place the crop with the box or the sliders. In "Crop to fill", "Crop size" runs from 30% to 100%, where 100% is the largest box of that shape. "Horizontal position" and "Vertical position" run from 0% to 100% and start at 50%, which is centred. Dragging the highlighted box moves the same two sliders; it cannot be resized by dragging. A press on the bottom 48 pixels of the preview is left to the player controls. Position only matters on the side with spare room: a 9:16 box in a 16:9 video moves sideways, not up or down. Sizes are rounded down to even numbers, so 607.5 becomes 606.
• Pick the shape for where the video will be posted. "Aspect ratio" offers 9:16 ("TikTok / Reels"), 1:1 ("Instagram"), 4:5 ("Portrait"), 16:9 ("YouTube"), 4:3 and "Free". The names are only labels. In Fit, "Output size" sets the short side of the new frame: at 1080p, 9:16 gives 1080×1920 and 1:1 gives 1080×1080; at 720p, 720×1280 and 720×720. A smaller clip is never enlarged, so a 640×360 clip fitted to 9:16 comes out at 640×1136. On a phone the size starts on 720p, which renders faster and gives a smaller file. In "Crop to fill" the output is the crop box itself, with no scaling.
• Choose a quality level for the file size. "High quality", "Balanced" and "Smaller file" encode H.264 at constant-quality values (CRF) of 18, 23 and 28. A lower number means better quality and a bigger file, and "Balanced" is the default. The result is always an .mp4 in the yuv420p pixel format. Fit mode uses the faster "veryfast" encoder preset to stay usable on phones. Audio from .mp4, .mov and .m4v files is copied unchanged; audio from other containers, such as WebM or MKV, is re-encoded as AAC at 128 kbps.
• Know the limits before adding a long clip. The tool takes one video at a time. It refuses a file above about 2 GB on a normal computer, 1 GB on a computer reporting 4 GB of memory or less, and 400 MB on a phone. It copies the whole video into the encoder's memory before cropping, so a file under the limit can still run out of memory. The first use downloads the encoder, about 31 MB, which the browser keeps afterwards. It starts loading as soon as you add the file, and "Encoder ready" appears when it is done. Your video is processed in the browser and is not uploaded.
• Change a setting to make a new version. A finished result is shown only while the controls still match it. Move a slider, or pick another mode, ratio, background, size or quality, and the player and the download button disappear and the main button comes back. "Crop again" runs the same settings once more. Under the download button, a "Do more with this file" row can pass the new .mp4 to other tools in the same browser tab, such as "Compress", "Add music", "Add captions" and "Make a GIF". Nothing is uploaded.

Common problems and how to fix them

It says "clip.mp4 could not be read. If it is stored in Google Photos, iCloud or a cloud drive, save it to this device first, then choose it again."

The page reads every picked file straight away, before the tool sees it. A phone copies picked files of up to 64 MB in total into memory at that moment; larger files get a one-byte test read. The usual cause is a cloud-only file that was never fully downloaded, or one that moved. Save it to the device and pick it from there. If a file changes after it was accepted, "Crop video" instead shows "This file changed or moved after you picked it — please choose it again."

It says "This browser couldn't start the in-browser media engine (WebAssembly), so your file was never processed. Reload the page; if it happens again, open this page in another browser. Strict security settings or extensions can block it."

The encoder was fetched, but the browser refused to start it: it reported a compile or link error, or said that code generation is disallowed. Nothing about your video is the problem, so choosing another file does not help. A failed start is not shown when you add the file; it appears when you press "Crop video", because that press tries to load the encoder again. Reload, then try another browser, or check the security settings and extensions that may block WebAssembly.

It says "Processing cancelled."

You pressed "Cancel" under the progress bar. Cancel stops the encoder at once and drops the half-finished file. The words appear in the red message box even though nothing is wrong. Press "Crop video", or the "Make 9:16 video" style button, again. The encoder is normally loaded again from the browser's cache, so there is no second 31 MB download.

It says "The browser ran out of memory processing this file — it's too large for this device. Try a shorter clip, a smaller file, or a desktop computer."

The whole input is copied into the encoder's memory, and the new file is built beside it, so both must fit at once. The tool picks this message when the engine reports that it ran out of memory. A phone has the lowest limits: files above 400 MB are refused outright, and smaller ones can still fail. Cut the clip shorter first, for example in the Video Trimmer, or use a computer. In Fit mode, 720p renders faster and gives a smaller file.

It says "This conversion failed — the format or codec may not be supported for this input. Try a different source file."

Every crop decodes the video and re-encodes it as H.264, so the in-browser engine must be able to read the input. The page shows this message when the engine's error mentions things like an unsupported codec, invalid data or a failed conversion. A damaged or half-copied file, or an unusual codec, can cause it. Convert the clip to a standard H.264 MP4 first, for example in the Video Converter, or try the original file again.

How it compares

"Crop to fill" gives a clean frame in a social shape at the cost of the edges, and "Fit (no cropping)" keeps every pixel of the picture and adds a blurred, coloured or black background instead. Both always re-encode the video to H.264 in an .mp4, so the result is re-compressed and not bit-for-bit the original. The crop box has a fixed shape: it keeps one of the listed ratios, and "Free" only zooms while keeping the video's own shape, so you cannot draw an arbitrary rectangle. The tool does not rotate, trim or scale a crop up to a larger size. For those jobs, or for files above the browser limit, use an editor on your computer. In exchange nothing needs installing, and the video stays in your browser.