Two formats built for two different jobs
PNG (Portable Network Graphics) arrived in 1996 as a patent-free replacement for GIF. It uses lossless compression built on the DEFLATE algorithm — the same math behind ZIP — so every pixel you save comes back byte-for-byte identical, no matter how many times you open and re-save it. It also supports a full alpha channel: each pixel can be fully opaque, fully transparent, or anything in between, at up to 16 bits per colour channel. That makes PNG the natural home for screenshots, logos, icons, line art, UI mockups, and anything with sharp edges, text, or flat blocks of colour.
JPG (or JPEG, the image standard first published in 1992 and later formalized as ISO/IEC 10918-1) works the opposite way. It's lossy: it slices the image into 8×8 blocks, runs a Discrete Cosine Transform on each, and deliberately discards the fine detail your eye is least likely to notice. That's why it's so good at photographs, where smooth gradients of light and colour hide the losses beautifully. But JPG has no alpha channel at all — transparency simply isn't part of the format.
Why a JPG is a fraction of the size
On a real photograph, the size gap is dramatic — a JPG is often five to ten times smaller than the same image saved as PNG. JPG earns that by quantizing detail and usually throwing away some colour resolution (chroma subsampling), tuned by a quality slider from roughly 1 to 100. PNG can't compete here because DEFLATE only shrinks things by finding exact repeating runs, and a photo of a face or a landscape has almost none.
Flip the content and the result flips too. On a screenshot or a logo — big areas of identical colour, crisp text — PNG compresses tightly and stays razor-sharp, while JPG both bloats the file and smears fuzzy 'ringing' halos around every hard edge. The right format depends entirely on what's in the picture, not on which one is 'better'.
The transparency trap when you go PNG to JPG
Because JPG has no alpha channel, converting a PNG with a transparent background forces a decision: what colour should those see-through pixels become? Every converter has to flatten transparency onto one solid backing colour. Many tools fill white; plenty fill black — a browser canvas, for example, treats un-touched pixels as black — which is why the same logo can land inside a white box on one converter and a black rectangle on another. Whatever the fill, the clean transparent edge you started with is gone.
There's no way around this — it's a limitation of the format, not the tool. What a good converter does is let you choose the backing colour so the flatten works in your favour. Our /png-to-jpg/ tool lets you pick that background (white, black, or any brand colour) instead of guessing for you, so the result sits cleanly on whatever page it's headed for.
Converting JPG to PNG won't bring quality back
This is the most common misconception about image formats. Saving a JPG as a PNG does not restore anything the JPG already threw away. The compression artifacts, the softened edges, the blocky patches in the sky — they're baked into the pixels. All PNG does is wrap those exact, already-degraded pixels in a lossless container, usually producing a much larger file that looks identical to the JPG you started with.
So when is /jpg-to-png/ genuinely useful? When you need to add transparency (say, to knock out a background afterward), when an editor or design tool demands PNG input, or when you want a lossless working copy you can edit and re-save repeatedly without stacking up fresh JPG compression each time. Just go in knowing it preserves quality — it can't rebuild it.
A simple rule for choosing
Ask one question first: does the image need transparency, or does it contain text, sharp edges, or flat colour? If yes — a logo, an icon, a screenshot, a diagram — use PNG. Otherwise, if it's a photograph and you care about file size (web pages, email, sharing), use JPG at around 80–90% quality; the size savings are enormous and the loss is invisible at normal viewing sizes.
The one case that catches people out is a photograph that also needs transparency — a product shot on a see-through background, for instance. JPG can't do transparency and PNG can't shrink a photo well, so you're stuck choosing which matters more. For that job, transparency usually wins, so reach for PNG (or WebP, if your destination supports it — most current browsers do, but some older apps and email clients still don't).
Convert either direction, privately, in your browser
Because these are just format conversions on your own images, there's no reason to hand them to a server. Both tools on this site run entirely in your browser — your PNG or JPG is decoded, re-encoded, and handed back to you on your own device, and the file is never uploaded anywhere. That matters for screenshots of private dashboards, unreleased designs, or personal photos you'd rather not scatter across someone else's cloud.
It also means conversion is instant and works offline once the page has loaded. Drop a file in, tune the settings, download the result — nothing leaves your machine.