What makes an image file big
| Factor | Effect on size |
|---|---|
| Pixel dimensions | Doubling width and height roughly quadruples the data |
| Format | PNG photos are much larger than JPG or WebP |
| Quality setting | Higher JPG quality keeps more detail and makes larger files |
| Detail and noise | Busy textures and grain compress less well |
The order that keeps photos sharp
- 1Crop away empty space so pixels go to what matters.
- 2Convert PNG or HEIC photos to JPG (or WebP for websites).
- 3Lower quality gradually; small drops cut size a lot before damage shows.
- 4Only if you still need a smaller file, reduce the pixel dimensions.
Which format to use
| Format | Best for | Note |
|---|---|---|
| JPG | Photos, marketplace uploads | Smallest widely accepted photo format |
| WebP | Your own website or store | Often smaller than JPG; not every upload form accepts it |
| PNG | Logos, text graphics, transparency | Large for photos |
| HEIC | iPhone camera originals | Convert to JPG before uploading |
Convert with the free HEIC to JPG, PNG to JPG or JPG to WebP tools.
Sizes sellers need
Marketplace photos need enough pixels for zoom, typically 1000 px or more on the longest side, but files don’t need to be huge. For product listings, resize to the marketplace’s recommended dimensions with the bulk image resizer, then compress to a few hundred KB. For forms with strict limits like 20 KB, crop tightly first.
