PNG and JPG are the two most common image formats on the web, and picking the wrong one means either a bloated file or a blurry, blocky picture. The good news: once you know what each format is built for, the choice is usually obvious.
We measured this ourselves. Running the same four test images through our PNG-to-JPG page: the photo fell from 1.88 MB to 288.4 KB, an 85% saving. The UI screenshot went the other way — 18.0 KB became 43.5 KB, up 142% — because JPG has to spend bits blurring the sharp edges PNG stored for free. The transparent logo came back with a white box behind it. see the full measurements
The short answer
The core difference between PNG and JPG comes down to how they compress and what they can store:
- PNG is lossless and supports transparency. Use it for logos, icons, screenshots and anything with sharp edges or text.
- JPG (also written JPEG) is lossy and produces much smaller files, but has no transparency. Use it for photographs.
If you need a transparent background or crisp text, choose PNG. If it’s a photo and you want a small file, choose JPG.
PNG vs JPG at a glance
| PNG | JPG (JPEG) | |
|---|---|---|
| Compression | Lossless — keeps every pixel | Lossy — discards fine detail |
| Transparency | Yes (alpha channel) | No |
| File size | Larger, especially for photos | Much smaller |
| Quality after re-saving | Never degrades | Drops a little each save |
| Best for | Logos, icons, text, line art, screenshots | Photos and realistic images |
| Colors | Up to 16M plus 8-bit alpha | 16M, no transparency |
PNG: lossless and transparent
PNG uses lossless compression, so it stores every pixel exactly — quality never degrades when you save, no matter how many times you re-export. It also supports transparency through an alpha channel, so a logo can sit on any background without an ugly white box around it. That makes PNG the right choice for:
- Logos, icons and illustrations with sharp edges
- Screenshots, especially ones containing text
- Line art, diagrams and flat-color graphics
- Anything that needs a transparent background
- Images you will edit and re-save repeatedly
The trade-off is size: a photograph saved as PNG can be several times larger than the same photo as JPG, because lossless compression can’t throw away the subtle noise and gradients that fill a real photo.
Transparency is where the choice becomes irreversible, and the number is smaller than people expect. Our transparent test logo is 28.8 KB as PNG; the same file through our PNG to JPG page comes out 16.3 KB (-43%) — cheaper, but with a white box where the transparency was. You are not trading quality for size here, you are trading a feature for size.
JPG: small and made for photos
JPG uses lossy compression: it discards detail the eye barely notices to make files dramatically smaller — often five to ten times smaller than a PNG of the same photo. There is no transparency. It shines for:
- Photographs and realistic images with smooth gradients
- Pictures you need to email, upload or post quickly
- Anywhere file size matters more than pixel-perfect fidelity
The catch is that each save discards a little more quality, so repeatedly editing and re-saving the same JPG slowly degrades it. Hard edges, text and flat areas of color can also pick up blocky “compression artifacts” — which is exactly why JPG is a poor fit for logos and screenshots.
The claim “JPG is smaller” fails on exactly one common input: a screenshot. Ours went 18.0 KB → 43.5 KB (+142%) — JPG has to spend bits blurring the hard 1-pixel borders that PNG stored almost for free. So the rule is not “JPG is smaller”, it is “JPG is smaller for photographs”.
The differences that actually matter
- Compression (lossy vs lossless). JPG trades a bit of quality for a much smaller file; PNG keeps the image perfect but pays in size.
- Transparency. Only PNG supports it. JPG always fills the background with a solid color.
- File size. For a photo, JPG almost always wins. For flat graphics with few colors, a PNG can actually be smaller and sharper.
- Quality over repeated edits. PNG is safe to open, edit and re-save endlessly. Each JPG save is generational loss you can’t undo.
- Detail and color. Both handle millions of colors, but JPG blurs fine text and sharp lines, while PNG keeps them crisp.
And the reverse direction is not symmetric, which is the part most comparisons leave out. Converting a photograph from JPG to PNG cost 330.2 KB → 2.07 MB (+542%) in our test, and a JPG screenshot 45.2 KB → 72.8 KB (+61%). Neither recovers anything: JPEG already discarded the detail, PNG merely stores what is left — artefacts included — at full price.
Two rows from our own measurements settle both halves of this comparison at once:
| Test image | Input | Output | Change |
|---|---|---|---|
| Logo with alpha | 28.8 KB | 16.3 KB | -43% |
| Screenshot | 18.0 KB | 43.5 KB | +142% |
The logo went 28.8 KB → 16.3 KB (-43%) — a genuine saving, except the alpha channel is gone and cannot come back, so the “saving” bought an image that no longer works on a coloured background. The screenshot went the other way: 18.0 KB → 43.5 KB (+142%), larger as a JPG, because JPEG spends bits describing the hard 1-pixel edges that PNG encodes almost for free. That is the real rule: JPG is not “the small one”, it is the one that wins on photographs and loses on everything flat.
When to use PNG vs JPG
- Need transparency? → PNG.
- A photo with no transparency? → JPG.
- Logo, icon, screenshot or line art? → PNG.
- File too big to upload or email? → JPG.
- A master copy you’ll keep editing? → PNG (export a JPG only at the end).
Common questions
Which has better quality? At the same content, PNG is technically perfect and JPG is “good enough.” But on an actual photograph you usually can’t see the difference — while the JPG is a fraction of the size.
Which file is smaller? JPG, for photos. For simple graphics with few colors, PNG often wins.
Which supports transparency? PNG. If you convert a transparent PNG to JPG, the transparent areas become solid (usually white).
Does converting JPG to PNG restore quality? No. Quality already lost to JPG compression is gone; wrapping it in PNG just makes a larger, lossless copy of the flawed image.
What about WebP and other formats?
WebP is a modern format that often gives you the best of both worlds — transparency and photo-grade compression, typically 25–35% smaller than JPG or PNG. It’s a great way to speed up a website for visitors on current browsers; see what WebP is and when to use it. If you’re choosing a format for a site from scratch, our guide to the best image format for the web walks through PNG, JPG, WebP and AVIF side by side.
Convert PNG and JPG, privately
You do not need to install anything. These free tools run entirely in your browser — your images are never uploaded:
- PNG to JPG — shrink a PNG photo for sharing.
- JPG to PNG — when you need a lossless copy or clean edits.
- PNG to WebP — modern, smaller web images.
- Compress an image — keep the format but cut the file size.
Choose the format that fits the job, convert in a couple of clicks, and you get the smallest file at the quality you actually need.