Every image format is a trade-off between file size, quality, and what kind of image it's compressing. Picking the wrong one is the single most common reason a photo looks worse than it needs to, or takes up far more space than necessary. Here's what actually separates the three formats you'll run into constantly.
JPG: built for photos
JPG throws away information the human eye is least likely to notice — subtle color gradients, fine texture — to achieve much smaller files than an uncompressed image. That trade works well for photographs, which are full of exactly that kind of gradual, forgiving detail. It works badly for anything with sharp edges or flat colors, like text, logos, or diagrams, where the compression shows up as visible fuzziness or blocky artifacts around hard lines.
Use JPG for: photographs, scanned photo prints, anything camera-captured where a small amount of quality loss is invisible at normal viewing size.
PNG: built for exactness
PNG compresses without throwing anything away — what you save is pixel-for-pixel identical to the original. That makes it the right choice whenever exact edges and flat colors matter: screenshots, logos, icons, diagrams, and anything with text baked into the image. The cost is size — a detailed photo saved as PNG can be five to ten times larger than the same photo saved as JPG, for a quality difference most people won't be able to see.
Use PNG for: screenshots, logos, graphics with transparency, scanned documents where text sharpness matters more than file size.
WebP: a newer middle ground
WebP was built by Google specifically to beat both of the above at their own games — it can compress photos smaller than JPG at similar quality, and it supports the same lossless, transparency-friendly mode PNG offers, at a smaller size. Browser and app support has caught up almost everywhere at this point, so the main reason to avoid it now is compatibility with older software that still expects a plain JPG or PNG, like some older printers, some government upload portals, or certain legacy editing tools.
Use WebP for: anything destined for the web, when you want smaller files than JPG/PNG without a visible quality trade-off, and you've confirmed wherever it's going actually accepts it.
A quick decision guide
- Photo, going on a website or social media → WebP, fall back to JPG if the destination doesn't accept it.
- Photo, printing or archiving → JPG at high quality, or the camera's original format if you have it.
- Screenshot, logo, or anything with text/sharp edges → PNG.
- A form or portal that specifies a format → follow exactly what it asks for; converting to the wrong format is a common reason uploads get silently rejected.
What this means for file size
If a form or email limit is forcing you to shrink an image, the format you're saving in matters as much as the compression setting. Converting a PNG screenshot to JPG before compressing it, for instance, often gets you a much smaller file for the same visual quality — because JPG's compression is simply more efficient for that data. Converting a photo the other way, from JPG to PNG, almost always makes it larger for no visual benefit.