What this tool does
Every crop request is really one of a small number of intentions: make it square, make it exactly 1200 by 630, shave the blank edge off a screenshot, or chop a long strip into separate images. Most crop tools offer one of those and leave the rest to a desktop app. This one covers all of them, plus rotation, mirroring and margin, and it never uploads your file.
How it works
Drag mode is the direct one: drag inside the box to move the selection, drag a corner to resize it, and drag an edge to change only that dimension. Locking an aspect ratio makes the box settle on an exact ratio rather than an approximate one, because the axis you move further decides the size and the other is calculated from it. The result is measured in whole pixels, so the crop is exact rather than off by a rounding artefact.
The calculated modes exist because dragging is the wrong tool for a repeatable job. Ratio takes the largest area at a preset ratio, centred, which is what an avatar or a video cover needs. Exact pixels takes a centred cut of precisely the size you asked for. Percent removes the same share from all four sides, so a batch of screenshots all lose the same border. Auto-trim reads the pixels to find the bounding box of everything that is not background, which handles a screenshot's white margin or a scanned page's paper edge without you measuring anything. Split divides the selection into a grid of equal tiles.
Auto-trim analyses a downscaled copy of the image rather than the full file. Scanning twenty-four million pixels for a uniform border would take long enough to look like a hang, so the image is scaled to about eight hundred pixels, the border is located there, and the answer is scaled back up. That is accurate to roughly one pixel on the original, which is far finer than the edge being detected. A transparent pixel always counts as background, since a padded PNG has no colour there to compare against.
Everything after the crop is a separate step, because these are decisions people usually want to make deliberately rather than have bundled in. Rotation swaps the output dimensions on a quarter turn, mirroring flips the pixels, and a margin adds a border outside the crop. When a margin is set, the source is re-encoded, so metadata including GPS coordinates does not survive into the file.
Worked example
A 2400×1600 press photo needs a 1200×630 crop for a link preview, and the same photo needs a separate 400×400 version for an author avatar.
- Choose Exact px and enter 1200 × 630
- The 3:2 source cannot fill a 1.9:1 frame, so the tool takes a centred 1200 × 630 cut
- Switch to 1:1 and enter 400 × 400 for the avatar
- Set Rotate to 90° on the portrait version to match the photographer's intent
Both files come out at exactly the requested pixels with no letterboxing and no distortion, and the press photo keeps full resolution rather than being scaled down to fit.
Accuracy and limitations
- A centred crop can cut the subject in half if it is not in the middle. Drag the box in Drag mode first for portraits, product shots and group photos.
- Cropping re-encodes the image, so a small amount of quality is lost each time. Work from the original rather than cropping an already-cropped file.
- Exact pixel mode cannot invent pixels. Asking for a size larger than the source in one axis gives you the source size, not the size you asked for.
- Auto-trim on a busy or textured edge can find a border that is not really there. Check the result, and raise the tolerance if it cuts too much or lower it if it cuts too little.
Frequently asked questions
- How do I crop an image to a square?
- Pick the Ratio mode and choose 1:1, or use Exact px with the same number in both fields. Ratio takes the largest centred square that fits, which is usually what an avatar or profile picture needs.
- How do I remove the white border around a screenshot?
- Use Auto-trim with 'Blank or matching border'. It finds the pixels that differ from the corner colour and crops to them. If the screenshot has a slightly off-white background, raise the colour tolerance until the unwanted edge is included in the trim.
- Can I crop to an exact size like 1200 by 630?
- Yes, that is what Exact px mode is for. It takes a centred crop of precisely that size. If your source is smaller than the target in one direction, you get the source size in that direction, because cropping cannot add pixels that were never captured.
- How do I split a long image into several pictures?
- Use Split mode, set the rows and columns, and the tool cuts the selected area into equal tiles. Each tile is a separate file you can download. Drag the selection box first if you only want to split part of the image.
- Does cropping reduce quality?
- Very slightly, because the cropped area is encoded into a new file. For lossless formats such as PNG there is no visual loss at all. For JPEG the loss is small at high quality but it compounds, so keep one original and crop from it each time.
- Is my photo uploaded to crop it?
- No. The image is decoded, cropped and re-encoded in your browser using the canvas API, and the file never touches a server.