PNG to JPG: When to Convert, When Not To

PNG is a great format that people use for the wrong things constantly. If you've screenshotted a photo, saved a camera image as PNG, or downloaded something that arrived as a needlessly heavy PNG, converting to JPG will often cut the file size dramatically with little or no difference you'd notice on a photograph.

Here's how to do it, and — more usefully — how to know whether you should.

Convert it

Drop your file into PNG to JPG and download the result. There's nothing to configure and nothing to install.

Why the file gets so much smaller

PNG is a lossless format: every pixel you put in is exactly the pixel you get back. That's a genuine feature, but it means PNG can't discard anything to save space. It compresses by finding patterns and repetition — which works brilliantly on flat colour and sharp edges, and poorly on photographic detail where almost every pixel differs slightly from its neighbour.

JPG is lossy. It discards image detail the encoder calculates most people won't notice, in exchange for a much smaller file. On a photograph that trade is close to invisible and the savings are large. That's the whole reason the conversion is worth doing.

When you should convert

• Photographs saved as PNG. The single most common case, and the one with the biggest payoff.
• Screenshots of photos or video. Screenshots of text and UI should stay PNG; screenshots of photographic content shouldn't.
• Anything hitting an upload size limit. Though if size is the real goal, see below — conversion isn't always the right lever.
• Anywhere a form demands JPG explicitly. Plenty of portals accept nothing else.

When you should not convert

This is the part most guides skip. Converting PNG to JPG is a bad idea when:

• Your image has a transparent background. JPG has no alpha channel at all. Transparency doesn't degrade — it gets filled in, usually with white or black. A logo with a transparent background becomes a logo on a solid rectangle. If you need transparency, stay on PNG or use PNG to WebP, which keeps it.
• It's a logo, icon, diagram, or screenshot of text. JPG's compression introduces fuzzy artefacts around sharp edges and small type. Flat-colour graphics are exactly what PNG is good at, and converting them often makes the file look worse and saves less than you'd hope.
• You'll keep editing and re-saving it. Every JPG save re-applies lossy compression, so quality compounds downward across rounds of editing. PNG never degrades on save.

If you only care about file size

Converting to JPG is one way to shrink an image, but it's not the only one and often not the best one. If the file is a photo and you need it under a specific limit, go straight to the number: Compress Image to 100KB or 50KB works backward from your target rather than making you guess.

If it's a graphic that needs to stay PNG, Compress PNG shrinks it without changing format or losing transparency. And if the image is simply larger in pixels than it needs to be, Resize Image usually beats aggressive compression — a 4000px-wide photo displayed at 800px is wasting most of its bytes on detail nobody sees.

Everything happens on your device

The converter runs entirely in your browser. Your image is decoded and re-encoded locally with the Canvas API — it's never uploaded to a server to be converted, which matters when the thing you're converting is an ID scan or a document rather than a holiday snap.

FAQ

Will converting PNG to JPG lose quality?
Yes, technically — JPG is lossy. On a photograph at a sensible quality setting, you almost certainly won't see it. On a logo or a screenshot of text, you likely will.

What happens to my transparent background?
It gets filled with a solid colour, because JPG cannot store transparency. If that matters, don't convert to JPG.

Can I convert back to PNG afterwards?
You can, with JPG to PNG, but it won't restore what the JPG compression discarded. The file becomes lossless from that point forward; it doesn't become original again.