JPG vs PNG: which should you use?

JPG and PNG are both just ways of packing pixels into a smaller file, but they go about it in opposite ways — and that one difference decides almost everything else about when to use each. Get the compression right for the image in front of you, and the rest (file size, sharpness, whether it supports transparency) mostly follows on its own.

The core difference: how they compress

JPG (JPEG) uses lossy compression. To shrink the file, it permanently throws away some of the image data — detail a viewer is statistically unlikely to notice, mostly small colour variations. That's a great trade for a photograph, where colours shift gradually across the frame anyway. It's a bad trade for anything with hard edges: text, line art, and flat-colour graphics come out of JPG compression with a soft, blocky halo around every sharp transition, an artifact usually called JPEG blocking.

PNG uses lossless compression. It packs the file more efficiently, but every single pixel comes back out exactly as it went in — nothing is discarded. That makes PNG the right choice whenever exactness matters: a screenshot, a logo, a chart, a scanned document, anything with legible text in it. The cost is file size: a PNG of a genuine photograph is often several times larger than an equivalent JPG, for a quality difference most people would never spot.

Transparency: the other big difference

PNG has a built-in alpha channel, so any pixel can be fully opaque, fully see-through, or anywhere in between — which is how a logo sits cleanly on top of a coloured background instead of arriving with a visible white box around it. JPG has no equivalent concept at all. Save a transparent PNG as a JPG and every transparent area gets filled in with a solid colour, almost always white. If a transparent background matters, PNG isn't just the better option — it's the only one of the two that works.

Why repeated saving hurts JPG but not PNG

Because JPG's compression is lossy, it's reapplied in full every time the file is saved — open it, make a small edit, save again, and a further, separate round of detail gets discarded on top of whatever was already lost the first time. Do that enough times and the cumulative effect (often called generation loss) becomes visible as smudging and blocky artifacts, even if each individual edit was trivial. A PNG doesn't have this problem: because nothing is discarded on save, opening and re-saving the exact same PNG a hundred times produces the exact same pixels every time. The practical takeaway: keep a working file as PNG (or another lossless format) while you're still editing it, and only export to JPG once, at the very end.

What about WebP and HEIC?

Two newer formats solve part of this tension. WebP supports both lossy and lossless compression in one format, plus transparency — genuinely the best of both JPG and PNG in most cases, and typically smaller than either at equivalent quality. The tradeoff is compatibility: a few older tools and some image-editing workflows still expect a plain JPG or PNG, which is usually the actual reason to convert a WebP file rather than any shortcoming in WebP itself. HEIC is Apple's default photo format on iPhone — it compresses more efficiently than JPG at similar quality, but support outside Apple's own ecosystem is inconsistent, so a HEIC photo often needs converting before it'll open, upload, or attach cleanly elsewhere.

Converting between formats

All of these run entirely in your browser — the image is never uploaded anywhere:

• JPG to PNG — for adding transparency or when a tool specifically requires a PNG
• PNG to JPG — to shrink a photo-style PNG down for web or email
• WebP to JPG and WebP to PNG — for compatibility with tools that don't yet support WebP
• HEIC to JPG — for an iPhone photo that needs to open outside Apple's ecosystem
• Compress Image — to shrink a JPG or PNG's file size without changing format

Common questions