Crop Image Online – Exact Pixels

Crop an image to exact pixels

Use this cropper when you need to keep one part of a JPG, PNG or WebP image and remove the rest. After choosing the file, drag the box on the preview or enter the crop rectangle in pixels: X from left is where the selected area begins horizontally, Y from top is where it begins vertically, and crop width and height set the output size. The result preview shows the selected image before download.

Choose X, Y, width and height

Image coordinates start at zero. An X value of 0 begins at the left edge; a Y value of 0 begins at the top edge. For example, a 400 by 400 crop with X 100 and Y 50 keeps a square whose top-left corner is 100 pixels from the left and 50 pixels from the top. The number fields and the box describe the same rectangle. If a crop reaches beyond the source image, this tool keeps the valid image area instead of inventing pixels.

Crop versus resize

Cropping removes outer pixels to change what is visible. Resizing changes the dimensions of the whole image. When a destination needs a square or a different shape, crop the useful area first, then use the existing image resizer to set its final pixel dimensions. This avoids stretching a wide or tall photo to fit a shape it did not originally have.

Crop for a social or upload shape

Start from the required output dimensions, then choose a crop that keeps the subject clear. After cropping, check the result dimensions and choose JPG for photographs, PNG where transparency or sharp graphics matters, or WebP for web delivery. For ready-made platform dimensions after selecting the visible area, use the existing social media image resizer.

Private image cropping in your browser

The crop is processed inside your browser; Image Cosmos does not upload the selected file to its server. Quality affects JPG and WebP output, while PNG is lossless and can be larger. Keep the original image as a master copy and use the existing image compressor only if a final file-size limit still needs attention.

How to crop an image with a box or exact pixels

1. Choose one JPG, PNG or WebP. It stays in this browser tab, up to 25 MB and 40 megapixels.
2. Select Free, a ratio such as 1:1 or 16:9, or a labelled social size. Drag the box to move it and a corner to resize it. Arrow keys nudge the focused box.
3. Use X, Y, width and height when you already know the pixels. X starts at the left edge and Y at the top, both from zero, and the fields follow the box.
4. Select Crop image, check the result width and height match the rectangle, then download. JPG, PNG or WebP follows the output menu, which starts as the file you opened.

How to crop an image

A crop keeps one rectangle and discards everything outside it. On this page that rectangle is a box drawn on the preview. Drag inside the box to move it. Drag any corner to change its size. The same gestures work with a mouse, a finger or a pen, because the box listens to pointer events. If you would rather use the keyboard, focus the box and press the arrow keys to nudge it by one pixel. Hold Shift to move ten pixels at a time. Focus a corner handle and the same keys resize from that corner.

Four number fields stay in step with the box: X from the left, Y from the top, width and height. Typing in a field moves the box, and dragging the box updates the fields. Coordinates start at zero on the top-left pixel, so X 0 and Y 0 is the corner of the picture, not the corner of the screen. A value that would run past the edge is pulled back. The tool does not add a border to make a crop fit, and it does not stretch the picture to invent a shape the file does not have.

Choose Free when the rectangle can be any shape. Choose 1:1, 4:5, 16:9, 9:16, 4:3 or 3:2 when the shape is fixed and only the position and the size should change. A locked ratio keeps that shape while you drag a corner or edit one side. The other side follows. If the size you ask for cannot fit, the box shrinks until it sits inside the picture.

Choosing a ratio

The ratio buttons do not set a file size and they do not set a platform rule. Each one places the largest rectangle of that shape that fits, centred, and you drag it onto the subject. A square, 1:1, suits a profile picture and a grid thumbnail. 4:5 is a tall portrait, useful when a feed post should be taller than a square. 3:2 is the classic stills-camera frame. 4:3 is common on older compact cameras and on a lot of slides. 16:9 is widescreen, the shape of most video frames and many thumbnails. 9:16 is the tall full-screen shape used for stories and short vertical video. Free is the right choice for a document, a screenshot or any subject that should not be forced into one of those shapes.

Social sizes, stated as they are

Three buttons ask for a pixel size as well as a shape. They place that exact rectangle in the centre when the image is large enough. When it is not, they fall back to the largest rectangle of the same shape, and the number fields show the pixels you will actually get. Nothing here enlarges a small photo to hit a social size. Extra pixels would only be a scaled-up crop, and that job belongs on the image resizer after you have chosen the area.

Instagram post 1080×1080 is a practical square, not a size Instagram’s help page prescribes. That help page says feed photos are processed at up to 1080 pixels wide. A square at that width is a sensible working canvas, and it matches the Instagram post size page on this site. The app can still present the upload differently, and it recompresses what you send. Instagram portrait 1080×1350 is the same kind of practical canvas in 4:5: the width is that 1080-pixel figure, and the height is 1080 × 5 ÷ 4, which is 1350 exactly. It is not a fixed upload requirement. The notes live on the Instagram portrait size page.

YouTube thumbnail 3840×2160 is a documented recommendation, which is why this button does not say 1280×720. The YouTube thumbnail size page records YouTube Help’s 3840×2160 figure for a standard-video custom thumbnail. That is 16:9. 1280×720 is a smaller 16:9 frame, and the 1280×720 resizer will make one from a crop, but it is not the thumbnail size this site cites. A 9:16 story or short is a different shape. Use the 9:16 button here, then read the Instagram story size page if you need the practical 1080×1920 canvas explained. This cropper does not add that story size as a pretend requirement.

If the whole picture must stay visible inside a frame of a different shape, that is not a crop. Cropping removes edges. Fitting keeps every pixel and adds a background where the shapes disagree. Both of those controls live on the social media image resizer. Use this page when you want to choose the rectangle yourself.

Crop and resize are different jobs

Resize changes how many pixels the whole picture uses. It does not choose a subject. Crop chooses a subject and leaves the remaining pixels at their original size. A 4000×3000 photo cropped to 1080×1080 is an 1080-pixel square taken from the original, not a shrunk copy of the whole frame. If the destination wants that square and also wants it 400 pixels wide, crop first and then resize the download. Shrinking the whole photo before you crop spends detail on edges you were about to throw away.

Stretching is the option to avoid for a face or a product. Turning a wide photo into a square by changing only the height, with no crop, squashes the subject. This page never does that. The output width and height are the width and height of the rectangle, in pixels. If you later need a print size in centimetres, millimetres or inches, take the cropped file to the resizer and set the print size there. The cropper does not write a DPI tag and it does not convert pixels into centimetres.

Quality and the format you keep

The pixels inside the rectangle are copied onto a new canvas. Cropping itself does not resample them, so it does not blur a sharp original. The file you download is still a new encode. JPG and WebP use the quality field, which runs from 10 to 100 and starts at 82. A lower number throws away fine detail so the file can be smaller. PNG ignores that number and is written losslessly, which keeps hard edges and transparency and often makes a larger file than the photograph you opened. The output menu starts as the format you opened: a JPG stays a JPG, a PNG stays a PNG and a WebP stays a WebP, unless you change it.

Because JPG and WebP are lossy, cropping a file you have already compressed is a second lossy save. Crop the camera original, or a PNG master, when you can, and keep that original. If a form also caps the file in kilobytes, crop here and then use the image compressor on the download, once. Running the cropped JPG through compression again after that rarely helps, and it can add blockiness. The result line shows the real width, the real height and the real file size before you save. Those dimensions should match the width and height fields. That match is the check that the rectangle you saw is the rectangle you downloaded.

A phone photo is sometimes stored sideways, with the orientation written beside the pixels rather than in the pixels. Current browsers show that photo upright, and this crop is taken from those same upright pixels, so the box lines up with the preview. The download is a new picture of the rectangle. It is not a byte-for-byte copy of the camera file.

The picture never leaves this tab

The browser reads the file, draws the rectangle and builds the download here. Image Cosmos does not receive the image, store a copy or keep a history of the crop. There is no account and no upload queue. The temporary download link disappears when you close or reload the page. The limit is one JPG, PNG or WebP at a time, up to 25 MB and 40 megapixels. Choosing another picture replaces the first. There is no batch list and no zip of several crops.

Advertising on the page does not receive the photo. The practical difference between this cropper and a site that asks you to wait for a server is that the file stays on the device the whole time. Judge the result at a size close to how you will use it, especially for type and for faces near the edge of the box, then download. If you only needed the whole picture at a new pixel size, with nothing cut off, the resizer is the shorter path. If you needed a kilobyte cap as well, crop, then resize if the pixels must change, then compress, each time from the file you meant to keep.

Frequently asked questions

How do I crop an image to an exact pixel size?

Open the picture, then drag the box or type X, Y, width and height. X is the left edge of the rectangle and Y is the top, both starting at zero. The output is that many pixels wide and tall. It is not a resized copy of the whole frame. If you need a different pixel count afterwards, resize the download.

What is the difference between cropping and resizing an image?

Cropping throws away the pixels outside a rectangle and leaves the rest at their original size. Resizing changes how many pixels the whole picture uses and does not choose a subject. Use a crop when a face, product or document should fill the frame. Use a resize when the destination asked for a width, a height or a print size and every part of the picture must stay.

Does cropping a photo reduce its quality?

The pixels inside the rectangle are copied, not redrawn, so the crop itself does not blur them. JPG and WebP are then saved again at the quality you set, which starts at 82, so a very low number can soften the file. PNG is written losslessly. Crop the original rather than a JPG you have already compressed, because each lossy save discards a little more detail.

How do I crop an image for an Instagram post?

Choose Instagram post 1080×1080 for a practical square, or Instagram portrait 1080×1350 for a practical 4:5 frame, then drag the box onto the subject. Those sizes match the canvases on the Instagram size pages. Instagram’s help describes feed photos processed at up to 1080 pixels wide. It does not require these exact heights, and the app can still crop or recompress the upload. If the photo is smaller than the button, the box becomes the largest matching shape that fits.

Can I crop an image without uploading it?

Yes. The browser reads the file, draws the rectangle and builds the download in this tab. Image Cosmos does not receive the picture, store a copy or keep a history of the crop. Close or reload the page and the temporary download link is gone. One image at a time, up to 25 MB and 40 megapixels.

How do I crop a picture to 16:9?

Select the 16:9 button. The box becomes the largest 16:9 rectangle that fits, centred on the picture, and you drag it to keep the subject. Corners stay locked to that shape. For a YouTube custom thumbnail, use the YouTube button instead: YouTube Help recommends 3840×2160, which is 16:9 at that pixel size, not 1280×720. If the photo is smaller than 3840×2160, you get the largest 16:9 area the file actually contains.

Why is the cropped image smaller than the social size I chose?

A crop cannot invent pixels. Instagram portrait asks for 1080×1350 only when the photo is at least that big. Otherwise the box is the largest 4:5 rectangle inside the file, and the width and height fields show those real pixels. The same rule applies to the 1080×1080 square and the 3840×2160 YouTube thumbnail. Enlarge afterwards with the resizer only if you accept a softer picture.