JPG vs PNG: Which One to Use
Use JPG for photos. Use PNG for anything with sharp edges, text, or transparency, like screenshots, logos, and graphics. That's the short answer. Here's why it holds up almost every time.
What actually separates them
JPG compresses an image by smoothing out small differences between pixels. This works well on photos because photos are full of gradual colour shifts, like skin tones or sky, where losing a little precision is invisible to the eye. The same trick performs badly on sharp edges, like the border of a letter in a screenshot, where it creates visible fuzzy halos called compression artifacts.
PNG doesn't smooth anything. It compresses without losing any data, which means text and hard edges stay perfectly crisp. The cost is a larger file, because PNG can't throw away the detail JPG throws away.
The file size difference is real
A photo saved as PNG is often 3 to 5 times larger than the same photo saved as JPG, for a difference in quality most people won't notice. A screenshot saved as JPG is often blurry around any text, for a file size saving that isn't worth the loss in clarity.
This is the actual reason the choice matters. It's not really about which format is "better." It's about which one wastes less for the specific image you have.
Transparency only exists in PNG
If you need a logo with no background, or an image that needs to sit cleanly over another colour, PNG is the only option between the two. JPG always fills the background with a solid colour, usually white, because it has no concept of transparency at all.
What about screenshots specifically
Screenshots are almost always PNG for a reason. They're full of flat colour blocks and sharp text, exactly what JPG compresses badly. If you've ever seen a screenshot that looks smudged around the text, it was very likely saved as JPG when it should have been PNG.
A quick way to decide
Ask what's in the image. A photograph, with continuous colour and light, wants JPG. Anything with text, icons, flat colour, or transparency wants PNG. If you're not sure, PNG is the safer default, since the only cost is a larger file, not a worse-looking one.
One thing worth knowing about repeated saving
Every time a JPG is opened and saved again, it loses a little more quality, because the compression is applied again on top of what's already there. This is called generational loss. PNG doesn't have this problem, since its compression never throws anything away. If you're editing an image multiple times, work in PNG and only convert to JPG at the very end.
Our image resizer works with both formats and resizes entirely in your browser, so nothing is uploaded to a server in either case.