Choosing the wrong image format is one of the most common and costly web performance mistakes. Using a PNG where a JPG would do triples the file size. Using JPG for a logo with transparency destroys the quality.
JPEG (JPG) — Best for Photos
JPEG is the world's most common image format. It uses lossy compression, meaning it discards some data to reduce size. This is invisible for photos but terrible for graphics with sharp edges, text, or transparency.
- ✅ Best for: Photographs, natural scenes, social media images
- ❌ Avoid for: Logos, screenshots, images with text, transparent backgrounds
PNG — Best for Graphics
PNG uses lossless compression — it preserves every pixel perfectly. It also supports full transparency (alpha channel). The trade-off is larger file sizes compared to JPEG.
- ✅ Best for: Logos, icons, screenshots, UI elements, anything needing transparency
- ❌ Avoid for: Photographs (unnecessarily large), backgrounds
WebP — The Modern Choice
WebP was developed by Google and offers the best of both worlds: lossy AND lossless modes, transparency support, and file sizes 25–35% smaller than JPEG or PNG for equivalent quality.
- ✅ Best for: Web images of any type — fastest loading
- ❌ Avoid for: When you need universal compatibility (some older software doesn't support WebP)