Rasp

Comparison

PNG vs JPG

The rule is simple and the failure modes are ugly. Photographs go in JPG; text and graphics go in PNG.

Should I use PNG or JPG?

Use JPG for photographs, where it produced a file 91% smaller than PNG on our test image with no visible difference. Use PNG for screenshots, logos, diagrams and anything containing text, where JPG's compression causes visible haloing. Use PNG whenever you need a transparent background, which JPG cannot store.

The measured difference

Both figures below come from converting the same source with this site’s own converters, over a fixed corpus.

PNG JPG
Photograph 3.97 MB 375 KB
Compression Lossless Lossy
Transparency Yes, including partial None
Text and sharp edges Exact Visible haloing
Repeated saving No degradation Degrades each time
Published 1996 1992

For a photograph, JPG is 91% smaller with no visible difference at normal viewing sizes. That is not a close call.

Why the rule is about content, not quality

The instinct is to treat this as a quality decision — PNG is lossless, therefore PNG is better. That reasoning gives you 4 MB screenshots of holiday photos and is wrong in both directions.

The real question is what the image contains.

Photographs are made of fine, continuous, slightly noisy variation. Lossless compression can find almost no exact repetition to exploit, so PNG stores something close to raw pixels. Meanwhile JPG’s approach — discard the high-frequency detail the eye is worst at — was designed for exactly this content and works beautifully.

Screenshots, logos and diagrams are the opposite. Large flat areas, exact repetition, hard edges. PNG compresses them superbly. JPG’s discarding of high-frequency detail is catastrophic, because a black letter against white paper is high-frequency detail. You get grey haloing around every character.

The two failure modes

Both are common, and both are visible at a glance once you know to look.

A photograph saved as PNG — the file is ten times larger than it needs to be. Nothing looks wrong; the page just loads slowly and the email bounces.

A screenshot saved as JPG — the file is small and the text looks slightly grubby. Zoom in and you will see grey fringing around the letters. This one is permanent: no amount of converting back to PNG removes it.

Transparency settles it outright

If the image needs a transparent background, JPG is simply not a candidate. It has no alpha channel and never has.

Converting a transparent PNG to JPG fills the transparency with a solid colour — white, on this site’s converter — and that is the correct behaviour rather than a bug. Something has to go behind it.

If you want transparency and a small file, the answer is neither format: convert to WebP.

For the web, both are the wrong answer

This is worth saying plainly, because the PNG-vs-JPG question is usually asked about a website.

WebP does what both do — photographic compression and transparency — and every current browser supports it. On our test image it was 94% smaller than PNG and 40% smaller than JPG.

PNG or JPG on a modern web page is usually a decision inherited rather than made.

Quick reference

  • Photograph, sent to a person → JPG
  • Photograph, on your website → WebP or AVIF
  • Screenshot or diagram → PNG, optimised losslessly
  • Logo with transparency, for print or a document → PNG
  • Logo with transparency, for the web → WebP
  • Working copy you will edit repeatedly → PNG

More on each: PNG, JPG.

Questions

Which is better quality, PNG or JPG?
PNG is lossless, so it is always a perfect copy of what it was given — but that does not make it the better choice. For a photograph, a JPG at a sensible quality setting is visually identical and a fraction of the size. Quality is only decisive when the image contains text or sharp edges.
Why is my PNG so much bigger than the JPG?
On our fixed test image, the same photograph was 3.97 MB as PNG and 375 KB as JPG. PNG stores every pixel exactly, and photographs are full of fine near-random detail with almost nothing to compress losslessly.
Should I use PNG or JPG for screenshots?
PNG, always. Screenshots are full of text and hard edges, which is exactly what JPG compression damages — you get visible haloing around letters that cannot be removed afterwards.
Can I get a transparent background with JPG?
No. JPG has no alpha channel and never has. Anything promising a transparent JPG is either producing a PNG with the wrong extension or filling the transparency with a solid colour.
Does converting JPG to PNG improve quality?
No. PNG stores exactly what it is given, and what it is given is the already-degraded output of JPG compression. You get a perfect copy of a lossy image — useful for further editing, useless as restoration.
Which is better for a website?
Neither, in 2026. WebP does what both do — photographic compression and transparency — in a much smaller file, and every current browser supports it. PNG and JPG on a web page are usually legacy decisions.
Is PNG or JPG better for printing?
Either works if the quality is high enough. PNG guarantees no compression artefacts; a JPG at quality 95 or above is generally indistinguishable in print. Check what the print service accepts — most take both.

Sources

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