PNG vs JPG: which image format to use, and when
The practical differences between PNG and JPG — compression, transparency, file size, quality — with a clear rule for photos, logos, screenshots and web images, and where WebP fits in.
PNG and JPG solve different problems. JPG (JPEG) is built for photographs: it throws away detail the eye does not notice and produces small files, but it cannot store transparency and every re-save loses a little more. PNG keeps every pixel exactly as it was and supports a full alpha channel, which makes it right for logos, icons, screenshots and anything with sharp edges or text — at the price of much larger files for photos.
The rule of thumb: photo or complex, full-colour image → JPG; graphic, logo, screenshot or anything that needs a transparent background → PNG. When file size matters on the web, WebP or AVIF beat both.
PNG vs JPG side by side
| PNG | JPG | |
|---|---|---|
| Compression | lossless — pixels stay identical | lossy — detail is discarded |
| Transparency | yes (alpha channel) | no |
| Colour depth | up to 48-bit, plus palette mode | 24-bit (8 bits per channel) |
| Best for | logos, icons, UI, screenshots, text | photos, complex images |
| File size (photo) | large | small — often 5–10× smaller |
| File size (flat graphic) | small | larger, with visible artefacts |
| Repeated editing | no loss | quality drops with each save |
| Animation | APNG (limited support) | no |
When JPG is the right choice
Photographs, scanned pictures, renders and anything with smooth gradients and millions of colours compress extremely well as JPG. At quality 80–90 a 12-megapixel photo is typically 2–4 MB as JPG versus 20 MB or more as PNG, and the two are indistinguishable at normal viewing size. Use JPG for photo galleries, product images, social media uploads and email attachments. Avoid it for text and line art: the compression blurs edges into visible “ringing”.
When PNG is the right choice
Anything that has a transparent background needs PNG (or WebP/SVG) — JPG fills transparency with white or black. Logos, icons, charts, screenshots of interfaces and images that contain text also stay crisp only in PNG, because lossless compression keeps every hard edge. PNG is also the format to keep while editing: you can open, change and re-save it endlessly without degradation, then export a JPG at the end.
File size in practice
For a flat graphic — a logo, a diagram — PNG is often smaller than JPG, because long runs of identical colour compress perfectly and JPG wastes bytes on artefacts. For a photo the relationship flips and PNG can be ten times larger. If a PNG photo is too big, converting it to JPG at quality 85 is the single biggest saving; if it must stay PNG, the compressor reduces the palette and strips metadata without visible change.
WebP and AVIF
WebP produces files roughly 25–35 % smaller than JPG at the same quality and supports transparency and animation; AVIF goes further still. Every current browser displays both, which makes them the best choice for website images. For files you send to people or upload to services that may not accept them, JPG and PNG remain the safe universal formats. imagenimble converts between all four locally.
Frequently asked questions
PNG is lossless, so it is never worse than the original; JPG discards detail. For photos at high quality the difference is invisible, for text and graphics PNG is clearly sharper.
For photos JPG — usually 5–10 times smaller. For flat graphics with few colours PNG is often smaller.
No. Converting a transparent PNG to JPG fills the transparent area with a solid colour. Use PNG or WebP if transparency is needed.
JPG for photos, PNG for logos and screenshots — or WebP for both, which is smaller and supported by all modern browsers.
No. Conversion runs entirely in your browser; nothing is sent to a server.