PNG vs JPG — Which Image Format Should You Use?

You exported your logo as a JPG and sent it to the client. They come back asking why there's a white box around it. Or the other way: you saved a product photo as PNG and now your page takes forever to load. Same image, different format, completely different problem.

This happens because JPG and PNG were built to solve different problems. Using the wrong one doesn't just waste file size, it actively breaks things.

JPG trades quality for weight, and that's usually fine

JPG uses lossy compression. When you save a JPG, the encoder throws away some image data permanently. It targets the details your eyes are least likely to notice, subtle color gradients, barely-visible texture transitions. For a photo of a market street or a mountain ridge, you genuinely won't see a difference between the original and a good JPG at 80% quality.

The file, though, can be five to ten times smaller than the PNG equivalent.

The tradeoff shows up in two situations. First: anything with sharp, clean edges. Text, logos, flat-color shapes. The compression algorithm produces blocky artifacts around hard boundaries, and they're impossible to miss. Second: repeated saves. Every time you re-export a JPG, it compresses what's already been compressed. The degradation compounds. Keep your working files in a lossless format and only export to JPG at the very end.

PNG preserves everything, at a cost

PNG is lossless. Every pixel is saved exactly as it was. Save the same PNG a hundred times, it comes out identical. That reliability is why PNG is the default for anything that needs to stay sharp: screenshots, interface mockups, diagrams, anything with text baked into the image.

The other thing PNG does that JPG cannot: transparency. Not just on or off, but full alpha channel support. Every pixel can be partially transparent. That's why logos, icons, and UI elements are always PNG. Place a transparent-background PNG over any color and it looks clean. Do the same with a JPG and you get the white box problem, because JPG has no concept of transparency at all. It fills the void with white.

The downside is file size. A photo saved as PNG can easily be 150 to 200% the size of the same photo as a JPG, with no visible quality gain. For web pages, that's a real cost.

The one question that decides it

Is this image a photograph of the real world?

If yes, JPG. The compression was designed exactly for this content, the artifacts hide in the complexity of the scene, and the size savings are significant.

If no, PNG. Logos, icons, screenshots, illustrations, anything with text, anything with a transparent background. These images have sharp edges and flat areas that JPG degrades visibly. And if you need transparency at all, PNG is your only option among the classic formats.

That split covers the vast majority of cases.

The mistakes worth knowing about

Saving a photo as PNG for a website is the most common one. A 4MB PNG and a 400KB JPG can look identical on screen, but one loads ten times slower. The browser doesn't care that the pixels are perfect.

Using JPG for a logo is the other classic. The white halo around the edges, the soft text, the compression noise on flat fills. Always use PNG or SVG for anything that needs to sit cleanly on a background.

There's also the archiving mistake. If you're editing photos, don't use JPG as your working format. Re-saving repeatedly destroys quality gradually. Keep originals as TIFF, PNG, or RAW and export to JPG only for delivery.

Where WebP fits in

WebP does what both JPG and PNG do, but smaller. It supports lossy and lossless compression, and it supports transparency. Modern browsers handle it without issue. If you're optimizing for web specifically, converting photos to WebP instead of JPG typically cuts file size by another 25 to 30% at the same visual quality.

It's worth considering for anything going on a public-facing page, especially product images or hero shots.

Quick reference

The table doesn't cover every edge case, but it handles the common ones. When in doubt, PNG is the safer starting point. You can always compress a PNG down to JPG later without losing the original. Going the other direction means working with whatever the JPG already discarded.