I cropped away about half the photo, so why didn't the file size halve, and sometimes even grow?
Because file size does not depend on pixel count alone. The cropper re-saves JPEG and WebP at a fixed quality of 92, which may be higher than the quality your original was saved at, and the part you kept is usually the most detailed part of the picture. So the file can come out heavier than you expect, and the fix is a separate compression step after cropping.
An example that shows the problem
You have a product photo measuring 4000 × 3000, which is 12 million pixels, with the product in the left half. You choose the 'Free' ratio in the Image cropper and keep only the left half, 2000 × 3000, which is 6 million pixels. The pixel count has halved exactly, but the file size will not necessarily follow, for two reasons.
Reason one: quality 92 is fixed
Many photos that reach you through chat apps or supplier websites have already been compressed at a low quality. When the cropper saves as JPEG or WebP it always uses quality 92, and there is no setting to change that. Quality 92 keeps more detail than a heavily compressed photo did, so each pixel takes more space, and the new file can land close to the original's size or above it, even though its dimensions are smaller.
That does not bring back detail the photo already lost. A higher quality faithfully stores what is there, old compression marks included.
Reason two: what you removed was cheap
A white background, a sky or a plain wall compresses into very little space because its pixels are alike. The product itself, with its texture, pattern and edges, is what uses most of the file. When you crop away the background and keep the product, you drop the light part and keep the heavy one, so the size falls far less than the share of pixels you removed.
And if you save as PNG?
PNG is lossless, and for a photograph its file is usually much larger than a JPEG. If you pick PNG under 'Save as', or your original was a PNG and you left 'Original format' selected, expect a big file. PNG suits logos and screenshots; for product photos JPEG or WebP is usually the better choice.
How to compare and fix it
- Once the photo loads, a line above it shows the file name, its dimensions and its original size. Note the size.
- Crop and download. A 'Download started' line appears with the new file name and its size.
- If the new size is more than you want, open the Image compressor, compress the cropped file at a lower quality such as 80, and compare before and after.
- Look at the result zoomed in on your phone, and if blotches appear around edges, raise the quality a little.
Always keep this order: crop first, then compress. If you compress first and crop afterwards, the file is written again at quality 92 and the compression gain is lost.
Common questions
Can I change the save quality in the cropper?
No. Quality is fixed at 92 for JPEG and WebP, and PNG is lossless. Use the compressor after cropping to control size.
Does a bigger file mean better quality?
Not necessarily. If the original was heavily compressed, saving it at a higher quality does not restore what was lost.
Which format should a cropped product photo use?
Usually JPEG or WebP, then compress if needed. Choose PNG only for transparency or text you want razor sharp.