PNG vs JPG: When to Use Each Format
The Fundamental Difference
JPG uses lossy compression — it permanently discards some pixel data to achieve smaller files. PNG uses lossless compression — every pixel is preserved exactly. This single distinction drives all the practical trade-offs between the two formats.
When to Use PNG
Choose PNG when you need transparency (alpha channel), when the image has sharp edges or text (logos, screenshots, UI mockups), or when you'll edit the file multiple times. Because PNG is lossless, re-saving it never degrades quality. Icons, diagrams, and anything with flat blocks of colour look best as PNG.
When to Use JPG
Choose JPG for photographs, gradients, and natural scenes. JPG excels at compressing complex imagery with smooth tonal transitions. A 24-megapixel photo might weigh 25 MB as PNG but only 5 MB as a high-quality JPG — with no visible difference at normal viewing sizes. Use JPG for web galleries, social media uploads, and email attachments.
File Size Comparison
At equivalent visual quality, JPG files are typically 5–10× smaller than PNGs for photographic content. For flat graphics, the gap shrinks — sometimes PNG is actually smaller than JPG because lossy artefacts force JPG to use more data around sharp edges. Test both and compare.
WebP: The Modern Alternative
Google's WebP format combines the best of both worlds — lossy and lossless modes, transparency support, and animation — all at smaller file sizes. It's supported by every major browser today. If backward compatibility isn't a concern, WebP is often the best default for the web.
Converting Between Formats
CocoConvert makes it easy to switch between PNG and JPG. Upload your file, pick the target format, and download the result. For batch work, the Pro plan lets you convert hundreds of files at once.