Quick answer: use JPG for photos and anything with lots of color and detail, since it compresses them into a small file size. Use PNG for graphics, logos, screenshots, or anything needing a transparent background, since it preserves sharp edges and flat colors exactly.

The Core Difference

JPG (or JPEG) uses "lossy" compression — it discards some image detail permanently to shrink file size, which works well because most of what it removes is detail the eye can barely notice in a photo. PNG uses "lossless" compression — it shrinks file size without discarding any data, which keeps every pixel exact but generally results in a larger file for complex images like photos.

When to Use JPG

  • Photographs with lots of color gradients and natural detail
  • Large images where file size matters, like website banners or blog photos
  • Any image where a small amount of compression won't be noticeable

Because JPG compression is adjustable, you can balance file size against quality — see how to compress an image without losing quality for a step-by-step approach.

When to Use PNG

  • Logos, icons, and graphics with flat colors and sharp edges
  • Screenshots containing text, where JPG compression can blur small letters
  • Images that need a transparent background, since PNG supports transparency and JPG does not

How File Size Compares

For a typical photo, a JPG at a reasonable quality setting is often five to ten times smaller than the same image saved as PNG, because PNG has to represent every subtle color transition exactly rather than approximating it. For a simple graphic with only a handful of colors, though, PNG can actually be smaller than JPG, since there's little detail for JPG's compression to work with in the first place.

Making the Right Choice Quickly

  1. Does the image need transparency? If yes, use PNG — JPG can't support it.
  2. Is it a photo or a graphic? Photos generally compress better and look fine as JPG; graphics and text-heavy images hold up better as PNG.
  3. Does file size matter more than pixel-perfect accuracy? If you're optimizing for a fast-loading webpage, JPG usually wins for anything photographic.

Common Mistakes

  • Saving photos as PNG "to be safe." This usually just produces an unnecessarily large file with no visible quality benefit.
  • Saving graphics or screenshots as JPG. Sharp text and flat colors can pick up visible blur and color banding from JPG's compression.
  • Not compressing either format at all. Even PNG files can often be optimized further without any visible change — see free image compressor.

Neither format is universally "better" — they're built for different kinds of images. Once you know whether you're working with a photo or a graphic, the right format usually becomes obvious.