The lossless-vs-lossy technical distinction between PNG and JPEG matters, but in day-to-day use, most people make the right choice faster by thinking about the type of content in the image rather than the underlying compression theory. A few practical rules of thumb cover the large majority of real situations. Getting this right consistently, across an entire body of published images rather than just occasionally, makes a noticeable, measurable difference in both how a site looks and how quickly it loads.

Use PNG for: graphics, text, and transparency

  • Logos, especially ones that need to sit on top of different colored backgrounds (requiring transparency).
  • Screenshots, particularly ones containing readable text or interface elements with sharp edges.
  • Simple illustrations or icons with flat colors and clean lines.
  • Any image where every pixel needs to stay exactly accurate, with zero compression artifacts.

Use JPEG for: photographs and continuous-tone images

  • Ordinary photographs — portraits, landscapes, product photos, event photography.
  • Any image with lots of subtle color gradation and natural texture, where JPEG's lossy compression is barely noticeable.
  • Situations where file size and load time matter more than pixel-perfect exactness, which describes most web and social media use.

Why using the wrong format for the content backfires

Saving a photograph as PNG produces an unnecessarily huge file for little to no visible quality benefit over a well-compressed JPEG. Saving a screenshot or logo as JPEG, on the other hand, tends to introduce visible compression artifacts specifically around the sharp edges and text that graphics are full of — exactly the content type JPEG's lossy compression handles worst. Matching the format to the content type avoids both of these common, easily preventable mistakes.

The edge cases worth knowing

A photograph that specifically needs transparency (a product photo with a removed background, for instance) is one of the genuine cases where PNG's larger file size is worth it despite the content being photographic, since JPEG simply can't support transparency at all. Conversely, a very complex, photographic-style illustration with lots of gradients and texture (rather than flat colors) sometimes compresses better and looks just as good as JPEG, even though it's technically "graphic" content rather than a photograph — the content-type rule of thumb is a reliable starting point, not an absolute law.

What to do when you're genuinely unsure

When a specific image doesn't clearly fall into either the "obviously graphic" or "obviously photo" camp — a photo-realistic illustration, for instance, or a screenshot that includes a photo within it — exporting both formats and comparing file size and visible quality directly, as covered in more detail in this site's PNG-versus-JPEG file size guide, settles the question more reliably than trying to force the image into one category or the other based on rules of thumb alone.

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Frequently asked questions

Is there ever a good reason to use PNG for an ordinary photo?

Mainly when the photo specifically needs transparency, since JPEG doesn't support it at all. Otherwise, a well-compressed JPEG or WebP typically looks just as good at a much smaller file size for ordinary photographic content.

Why does a JPEG screenshot sometimes look blurry around text?

Because JPEG's lossy compression is specifically less effective at preserving sharp edges and fine detail, which is exactly what text and interface elements in a screenshot are made of, making PNG the more reliable choice for that kind of content.

Does it matter if I get the format choice slightly wrong?

For casual, low-stakes use, not hugely — but for a website or any use case involving many images, consistently choosing the wrong format across a large content library adds up to real, avoidable file size and quality costs over time. Building this simple habit into a regular publishing or content workflow, rather than deciding format case by case from memory, tends to produce more consistent results across a large image library over time. Consistency across a growing library pays off substantially, since a mismatched format buried somewhere in an old archive is far more tedious to track down and fix later than to simply get right from the start.