Prepare images for upload limits without needless quality loss

Keep the original and read the requirement

Before changing anything, save the original separately. An upload rule may specify a file-size ceiling, pixel dimensions, an aspect ratio, or a format; solving the wrong constraint can make an image worse without fixing the rejection.

Crop only when the composition or required aspect ratio calls for it. Cropping removes pixels permanently, so it is not a substitute for compression.

Resize before compressing

If an image is much larger than its final display size, reduce pixel dimensions first. A 4000-pixel phone photo used as a 1200-pixel listing image carries detail the listing cannot show, and shrinking it often saves more space than pushing compression quality down.

Then use the Image Compressor. Start around quality 75 for photos and compare the preview at the details that matter: text, faces, edges and gradients. Lower the setting only until the file meets the target.

Choose format for the image, not the file extension

JPG is usually appropriate for photographs. PNG is for graphics or images needing transparency, but can be unexpectedly large for a photo. WebP can make a smaller upload when the destination accepts it.

If the destination only accepts JPG or PNG, convert deliberately and check the result. Changing a filename extension does not convert the image data and will not satisfy a format check.

Example: 1200 × 800 pixels and under 500 KB

For a 4000 × 3000 photo, a 1200 × 800 requirement has a different shape. First use Crop Image at 3:2 and keep the subject inside the selection. Download the crop, open it in Resize Image with the ratio locked, and enter width 1200; height should become 800.

Check that resized download before adding another compression step. If it already meets the byte limit, stop. Otherwise open it in Compress Image, choose a permitted format, and adjust quality while checking the reported size and detail. A quality setting of 75 is a starting point, not a promise of 500 KB.

Use PNG for intermediate downloads when you want to avoid repeated lossy encoding, then make the final JPG or WebP once. Transparent areas become white in JPG. Keep a little space below the upload ceiling because sites may interpret KB differently.