PNG vs JPEG: Which Image Format Should You Use?

PNG and JPEG are the two formats every digital image eventually gets saved as. They look similar at a glance but compress in completely different ways and serve different purposes. Pick the wrong one and you either get a blurry mess or a file that's 10× bigger than it needs to be.

The 30-second answer:

• Photographs → JPEG (or WebP, which beats both).
• Screenshots, logos, line art, anything with sharp edges or large flat-color regions → PNG.
• Anything with transparency (logos on dark backgrounds, UI assets) → PNG, full stop.

If you want the reasoning, read on.

How they compress

JPEG uses lossy compression — it throws away image data the human eye is unlikely to notice. It's optimized for natural images: the algorithm transforms 8×8 pixel blocks into the frequency domain, discards high-frequency components (fine detail), and quantizes the rest. The result is dramatically smaller files for photographs, but visible artifacts (blocking, ringing) on sharp edges and text.

PNG uses lossless compression — every pixel of the original is preserved exactly. It's based on DEFLATE (the same algorithm as ZIP), preceded by a per-row prediction filter that makes the data more compressible. PNG is excellent at compressing flat color regions (like UI screenshots or vector illustrations rasterized to a fixed size) and terrible at compressing photographs (which are mostly noise from a compression standpoint).

When JPEG wins

A 12-megapixel phone photo saved as PNG is typically 15–30 MB. The same photo saved as JPEG at quality 90 is 2–4 MB. The visual difference is essentially zero.

Rule of thumb: if you can describe the image as "a photograph," use JPEG. Save it at quality 85–92 — that's the sweet spot where files are small but artifacts are invisible at normal viewing distances.

When PNG wins

PNG wins anywhere edges and flat colors dominate:

• Screenshots. A PNG screenshot of a webpage is usually 10–30% the size of the same screenshot saved as JPEG, and JPEG would introduce visible ringing around the text.
• Logos and icons. Sharp edges with two or three colors compress beautifully in PNG.
• Line drawings, comics, pixel art. Same reason.
• Anything with transparency. JPEG has no alpha channel; if you need part of the image to be transparent, PNG is your only option (other than WebP or TIFF).

When neither wins — use WebP

WebP supports both lossy and lossless modes plus transparency, and it's smaller than both JPEG and PNG in their respective domains. If your audience uses modern browsers and the image is destined for the web, convert to WebP instead.

The conversion gotchas

• PNG → JPEG loses transparency. JPEG has no alpha channel; transparent regions become whatever fill color the converter picks (usually white or black). Convert PNG to JPEG if you don't need transparency; otherwise stick with PNG.
• JPEG → PNG doesn't gain quality. The original JPEG already discarded data; converting to lossless PNG just preserves the discarded version. Use this only when you need transparency added in a later step or to stop further degradation through repeated re-saves.
• Repeated JPEG saves degrade quality. Every save loses a little. If you're going to edit and re-save multiple times, work in PNG or TIFF and only export to JPEG at the end.

Quick decision tree

1. Does it have transparency? → PNG (or WebP).
2. Is it a photograph? → JPEG (or WebP).
3. Is it a screenshot, logo, or line art? → PNG.
4. Web-only and audience uses modern browsers? → WebP beats both.

To convert in either direction: Compress Image handles both formats with a quality preview, all in your browser. Or hop straight to a specific conversion:

• PNG to JPEG
• JPEG to PNG
• PNG to WebP
• JPEG to WebP

FAQ

What about TIFF? TIFF is lossless like PNG but has fewer compatibility quirks for archival and print workflows. It's the right format for "I'll never re-encode this" scans and for sending files to a printer; not the right format for the web (file sizes are huge and browser support is patchy).

What about HEIC? HEIC is what iPhones save photos as by default. It compresses ~50% better than JPEG at the same quality but is poorly supported outside Apple's ecosystem. Convert HEIC to JPEG before sharing if your recipient isn't on a Mac or iPhone.

Can I convert between PNG and JPEG without losing quality? PNG to JPEG always loses something (lossy compression). JPEG to PNG doesn't add loss but doesn't recover what JPEG already threw away.