PNG vs JPG: which one should you actually use?
When PNG wins, when JPG wins, why transparency turns white on conversion, and how much file size each format really saves.
The real choice isn't "PNG or JPG" in the abstract — it's lossless vs. lossy, and transparency vs. photography. Need a transparent background, or is the image text/UI with hard edges? Use PNG. Is it an ordinary photo with no transparency? JPG almost always wins on file size with no visible quality loss. Try both and compare the output with Docuboxer's image converter for PNG, JPG, and WebP, which runs entirely in your browser — nothing gets uploaded.
Why a PNG photo is 5-10x heavier than the equivalent JPG
PNG uses lossless compression: it rebuilds the file pixel-for-pixel, identical to the source. That works great when an image has few repeated colors — a logo, an icon, a UI screenshot — because the compressor finds patterns to squeeze out. But a real photograph is full of smooth gradients and sensor noise: millions of nearly unique color values, pixel by pixel. Lossless compression finds almost nothing to compress there, and the file stays heavy.
JPG takes a different approach: it throws away information the human eye barely perceives (mostly fine color detail) and compresses aggressively what's left. The result is that a photo weighing 8 MB as PNG might weigh 1 MB as JPG, with minimal visible difference. That's the technical reason almost no website serves photos as PNG — the file-size savings from JPG translate directly into faster page loads.
Converting JPG to PNG doesn't recover quality
This is a common misconception: someone has a JPG with visible compression artifacts and converts it to PNG hoping to "fix" the image. It doesn't work that way. JPG's lossy compression already decided, at the moment the original file was saved, what information to throw away — and that decision can't be undone. The resulting PNG contains exactly the same artifacts, just stored in a larger file, since PNG doesn't compress lossily on top. You're converting the container, not the quality.
The only real way to recover quality is to start from an uncompressed or less-compressed original and re-export from there. If all you have is the degraded JPG, no converter — Docuboxer's or anyone else's — can invent detail that no longer exists.
Transparency: the factor that makes the decision for you
If your image needs transparent areas — a logo that sits on different colored backgrounds, an icon, a UI element — the decision is already made: JPG has no alpha channel. Try converting a transparent PNG to JPG and the converter has to fill those areas with a solid color, almost always white, which is exactly why you sometimes see a logo suddenly gain a white box around it after conversion.
For logos and graphics that need transparency, WebP is worth considering as an alternative to PNG — it also supports an alpha channel but compresses better. And if the logo is made of simple shapes — text, lines, basic geometry — it's worth asking whether you need a pixel format at all: an SVG weighs a fraction of either and stays sharp at any size. You can convert between PNG/JPG and SVG with the SVG converter.
Text and screenshots: why JPG produces halos
JPG compresses by splitting the image into blocks and smoothing transitions within each block — great for photographic gradients, bad for hard edges. Text, UI icons, and straight lines all have an abrupt color change from one pixel to the next, and that's exactly where JPG compression produces visible color blotches and halos around the edge, often called "blocking artifacts."
That's why screenshots, diagrams, and any image with readable text should be saved as PNG, never JPG. If the resulting PNG is too heavy, the fix isn't switching to JPG and losing sharpness — it's shrinking the dimensions with the image resizer or compressing the PNG without quality loss using the image compressor.
Generation loss: re-saving a JPG degrades it every time
Every time you open a JPG, edit it — even a simple crop — and save it again, the app runs a fresh pass of lossy compression on data that already lost information in the previous save. This is called generation loss: after several open-edit-save cycles, new blotches and halos appear that weren't in the original file, even if you never changed the quality setting.
PNG doesn't have this problem, because its compression is lossless and reversible — opening and re-saving a PNG a hundred times produces exactly the same pixels on the hundredth save as the first. If you're editing an image across several steps (crop, adjust, crop again), work in PNG throughout and export to JPG only once, at the very end.
Favicons and icons: a case where neither one wins outright
Favicons are a good example of why "PNG vs. JPG" is sometimes the wrong question. They need transparency (which rules out JPG), but they're also displayed at tiny sizes and on high-density screens, where file weight barely matters since they're a few kilobytes in any format. PNG is the practical choice here, and you can generate one directly with the favicon generator.
When the right answer is neither PNG nor JPG
For most photos published on the web, PNG is the wrong default — it costs too much file weight for the benefit it provides. But JPG isn't always optimal either. Modern formats like WebP and AVIFcombine the best of both: they compress photos better than JPG at comparable quality, and they support transparency like PNG. If your project and audience support them, they're almost always the better choice today — Docuboxer's converter exports to WebP right alongside PNG and JPG.
And when the content isn't a photo but a vector drawing — a logo, an icon, a simple line illustration — the right answer is usually neither pixel format: an SVG weighs less than both and never loses sharpness, no matter what size it's displayed at.
Quick reference
- Photo with no transparency: JPG (or better, WebP).
- Logo, icon, or anything with transparency: PNG (or WebP if size matters).
- Screenshot, text, diagram: PNG. JPG produces visible halos.
- Editing across multiple steps: work in PNG, export to JPG only at the end.
- Simple geometric shape (logo, icon): consider SVG before either pixel format.
Frequently asked questions
Why is a PNG so much bigger than the equivalent JPG?
Because PNG is lossless — it stores the exact value of every pixel. A photograph has millions of subtle, non-repeating color variations, so lossless compression barely shrinks it. JPG is built specifically for photos: it discards detail the eye rarely notices and compresses far more aggressively. For an ordinary photo, a PNG can end up 5-10x heavier than a visually identical JPG.
If I convert a JPG to PNG, do I get the lost quality back?
No. JPG's compression artifacts are already baked into the pixel data — converting the file to PNG just stores those same artifacts losslessly, in a bigger file. It's like photocopying a blurry photocopy onto better paper: the blur doesn't go away, only the paper changes. The only fix is re-exporting from a higher-quality original, if you still have one.
Why does my PNG turn white when I convert it to JPG?
JPG has no alpha channel, so it can't represent transparency at all. If your PNG has transparent areas — common in logos — the converter has to fill them with a solid color, almost always white, when it saves as JPG. If you need to keep transparency, JPG simply isn't an option; stick with PNG or move to WebP.
JPG or PNG for screenshots and text?
PNG. JPG's block-based compression assumes smooth photographic gradients, and it struggles with the hard edges in text, UI icons, and straight lines — producing visible color halos and blotches around every letter. PNG reproduces sharp edges exactly, which is why screenshots and diagrams should never be saved as JPG.
Does re-saving a JPG multiple times degrade it further?
Yes — this is called generation loss. Every time you open a JPG, edit it, and save again, a fresh round of lossy compression runs on data that already lost information in the previous save. After a few cycles, new blotches and halos appear that weren't in the original. PNG doesn't have this problem: its compression is lossless and reversible, so opening and re-saving never loses data.
When is neither PNG nor JPG the right answer?
When you want photographic quality at a smaller file size than PNG. That's what WebP and AVIF are for — modern formats that compress photos better than JPG while also supporting transparency like PNG. And if the content is a logo or icon made of simple shapes, you may not need a pixel format at all: SVG represents it as vectors, at a fraction of the file size and with perfect sharpness at any scale.
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- Convert image to PNG, JPG, or WebP — The main converter for this article.
- Compress image — Shrink a PNG or JPG without changing format.
- Resize image — Adjust dimensions before or after converting.
- Convert to SVG — When the content is vector art, neither PNG nor JPG is the answer.
You might also like: converting HEIC to JPG.