1. The file is too heavy
The most common one by a long way. A 12-megapixel phone photo is routinely 5 to 8 MB. Etsy, eBay and most contact forms have their own ceilings, and a set of ten photos hits them fast.
The fix is compression, and it is worth understanding what compression actually does: it throws away detail your eye will not miss at the size the image is viewed. At 80% quality most photographs are visually identical and a fraction of the size.
Where it goes wrong is compressing something that was already compressed, over and over. Each pass throws more away. Always go back to the original.
2. The format is wrong
iPhones shoot HEIC by default. It is an excellent format and almost nothing on the web accepts it. The photo is perfectly fine — the container is one the site does not understand.
The other direction catches people too: a cut-out saved as JPG loses its transparency, because JPG has no alpha channel. The transparent area becomes white, and you find out when it is already on the listing.
3. The connection gave up
This one is unfair and it is why it is worth naming. On a slow or unstable line a large upload can time out halfway, and the site will report it as a file problem rather than a network one.
You can tell them apart: if a small photo uploads and a large one does not, it is the connection, not the format. Compressing helps here for the same reason it helps everywhere else — there is simply less to send.
This is the whole reason our compressor, converter and resizer run inside your browser rather than on a server. Nothing has to be uploaded to fix an upload problem, which would be an unusually stupid design.
A routine that stops all three
- Get the original off the phone properly — cable or email, not WhatsApp.
- Convert to JPG if it is HEIC.
- Resize to what the marketplace actually shows at.
- Compress to about 80%.
- Upload.
Four steps, under a minute for a whole set once you have done it twice. The compressor, converter and resizer all run in your browser and cost one credit each.