A photo is framed for the moment it was taken, not for the box it eventually has to sit in. A profile picture wants a square, a video thumbnail wants 16:9, a product shot wants the subject filling more of the frame. Cropping fixes all three: you choose a rectangle inside the picture and everything outside it is discarded. This guide covers what cropping changes, how ratio locking works, how to crop to exact pixels, and how cropping differs from resizing and compressing - with a worked example you can follow in the Crop Image tool.
What cropping actually does
An image is a grid of pixels. Cropping copies a smaller rectangle out of that grid and throws the rest away. The pixels you keep come across exactly as they were - same resolution, same colours, same sharpness - so cropping is one of the few edits that cannot soften a photo. That is the difference from resizing, which rebuilds the whole grid and has to average pixels to do it.
What does change is the pixel count, and file size follows it roughly in proportion to area. A 12-megapixel phone photo is 4032x3024, or 12,192,768 pixels. Take the largest square out of it and you get 3024x3024 - exactly 75% of the original, because you kept 3024 of the 4032 columns and every row. Framing changes too: cropping in tight makes the subject larger, but no extra detail appears, so a hard crop of a small image looks soft displayed large.
Cropping in the browser, step by step
- Drop a PNG, JPG or WebP onto the Crop Image tool, or click to choose one. The file is read from your device - nothing is uploaded.
- A selection box appears covering 80% of the picture, centred, with a grip on each corner and edge and rule-of-thirds lines inside.
- Pick an aspect ratio, or leave it on Free for any shape.
- Drag inside the box to move it, or a grip to resize it. The box cannot leave the image.
- Check the readout below - it shows the original and the crop size in pixels.
- Choose PNG or JPG, then download. Reset puts the box back around the whole image.
Locking an aspect ratio
An aspect ratio is the shape of a rectangle expressed as width against height, independent of size: 1:1 is a square, 16:9 a widescreen video, 9:16 a phone screen upright. Anywhere an image must fit a fixed slot, the slot has a ratio, and cropping to it yourself is how you control what gets cut.
Choosing a preset fits the largest box of that shape inside your image, centres it, and keeps the shape locked while you drag. On a 4032x3024 photo, 1:1 gives a 3024x3024 box starting 504 pixels from the left, because (4032 - 3024) / 2 = 504. Picking 16:9 gives 4032x2268 sitting 378 pixels down, since 4032 x 9 / 16 = 2268 and (3024 - 2268) / 2 = 378. Picking 4:3 selects the whole image, because 4032x3024 is already 4:3.
The presets cover the common shapes: 1:1 for profile pictures, 16:9 for thumbnails and slides, 4:3 and 3:2 for photo prints, 3:4, 2:3 and 9:16 for portrait crops. Anything else - Instagram's 4:5, for instance - is a job for the pixel fields below.
Cropping to exact pixels
Under the picture are four number fields: X, Y, Width and Height, in pixels of the original image. X and Y are measured from the top-left corner, so X 504, Y 0 starts the crop 504 pixels in from the left, flush with the top. Typing into them moves the box and dragging the box updates them - two views of one selection, so you can rough it out by eye then round the numbers by hand.
Every value is clamped to stay inside the image, which explains behaviour that looks like a bug: if your box is 320 wide on a 400-wide image, X will not go past 80, because 80 + 320 is the full width. Shrink the width first and X moves further. With a ratio locked, changing one dimension changes the other.
A worked example: a profile picture from a phone photo
Say you have a 4032x3024 landscape photo and need a square avatar. Load it into Crop Image and click 1:1. The box snaps to 3024x3024 at X 504, Y 0 - the biggest square the photo can give. Your subject is rarely dead centre, so drag the box left or right until the face sits where you want it; only X changes, because a full-height square has nowhere to go vertically.
To make the head larger in the frame, pull a corner grip inwards. The box stays square and the readout counts down - stop at, say, 2000x2000. Download as PNG and every pixel is at its original quality.
Most avatar slots are far smaller, so the last step is to shrink it: run the square through the Image Resizer at 1080x1080. Crop first, then resize - that order lets you choose the framing before any pixels are averaged away. The other way round throws away detail you then have to crop into.
Crop, resize or compress?
- Crop changes what is in the picture. Use it when the framing or the shape is wrong - too much sky, a distracting edge, a landscape photo that needs to be square.
- Resize changes how many pixels describe the same picture. Use it when the framing is fine but the image is too big or too small for where it is going.
- Compress changes how efficiently those pixels are stored. Use it when the dimensions are right but the file is too heavy for an upload limit.
They stack in that order. If what you need is a passport or visa photo, skip the lot and use the Passport Photo Maker, which crops to official sizes at print resolution.
PNG or JPG on the way out
PNG is lossless and keeps transparency - the right choice for logos, screenshots and diagrams. JPG re-encodes the image into a much smaller file, which suits photographs, but cannot store transparency: transparent areas are filled with white. Crop to PNG if the result will be edited again, to JPG if it is going straight to a website or upload form. To change format afterwards, use the Image Converter.
If something looks wrong
- The crop is smaller than expected. Trust the readout, not the box - the preview is scaled to fit the page.
- The box will not move further. It is clamped to the edge of the image. Reduce the width or height first, then move it.
- The result looks soft when enlarged. Cropping cannot add detail - a 300x300 crop shown 900 pixels wide is stretched threefold. Take a larger crop.
- Transparency turned white. That is JPG doing what JPG does. Crop again and choose PNG.
Crop your image now
Cropping is a ten-second job: load the photo, pick a ratio or drag freely, check the readout, download. Open the Crop Image tool and take the rectangle you actually want - free, no sign-up, no watermark, processed entirely in your own browser.
Frequently asked questions
- Does cropping an image reduce its quality?
- No. The pixels inside the box are copied across at their original resolution and nothing is resampled, so the part you keep is exactly as sharp as it was. What changes is how many pixels you are left with - crop a 4032x3024 photo down to 600x600 and you have a perfectly sharp 600x600 image, but it will look soft if you then display it a thousand pixels wide. Choosing PNG keeps the result lossless; choosing JPG re-encodes it, which is a small quality cost in exchange for a much smaller file.
- How do I crop an image to an exact size in pixels?
- Use the X, Y, Width and Height fields under the preview. Width and Height set the size of the crop and X and Y set where it starts, measured from the top-left corner of the original. Set the width and height first, then the position - the values are clamped so the box always stays inside the image, so a box that is already as wide as the space remaining will refuse to move further right until you shrink it. Dragging the box on screen updates the same numbers, so you can rough out the framing by eye and then type exact values.
- Are my images uploaded when I crop them online?
- No. The image is read straight from your device, the crop is drawn onto a canvas in the page, and the result is handed back as a download - it is never sent to a server and no copy is kept anywhere. That matters for the things people most often crop, which tend to be personal photos, screenshots containing private information and scans of documents. It also means the tool keeps working with no connection once the page has loaded.