PNG vs WebP vs JPEG: Which Image Format Should You Use?

Every image format decision is a tradeoff between file size, quality, transparency support, and browser compatibility. Pick the wrong format and you're either bloating your page load time or degrading image quality unnecessarily. Here's the definitive comparison so you can make the right call every time.

JPEG: The Photo Standard That's Been Good Enough

JPEG (1992) uses Discrete Cosine Transform to divide an image into 8×8 pixel blocks, transform them to frequency domain, and quantise (discard) high-frequency data that human eyes care less about. The quality parameter controls how aggressively high frequencies are discarded.

Use JPEG for: Photographs, complex scenes with many colours and gradients, backgrounds without sharp edges. At quality 85, JPEG is visually indistinguishable from the original for most photographs.

Never use JPEG for: Logos, icons, screenshots with text, anything with transparency. JPEG artefacts are most visible at hard edges (text, diagrams) and it destroys transparency entirely — replacing it with white.

PNG: Lossless and Transparent, But Expensive

PNG uses lossless DEFLATE compression — every pixel is preserved exactly. PNG-8 supports 256 colours with 1-bit transparency (on/off). PNG-24 supports full 24-bit colour with an 8-bit alpha channel (256 levels of transparency).

Use PNG for: Logos, icons, UI elements, screenshots with text, any image that needs transparency with hard edges, and any time you need pixel-perfect reproduction.

Never use PNG for: Photographs intended for web delivery — a 2MB PNG photo that could be a 250KB JPEG is indefensible.

WebP: The Modern Default for the Web

WebP supports both lossy and lossless compression, transparency, and animation — making it a genuine replacement for all three traditional formats. It uses a modern entropy coding scheme (VP8 for lossy, VP8L for lossless) that consistently outperforms both JPEG and PNG.

Real-World File Size Comparison

The Decision Tree

SVG: The One Format We Haven't Mentioned

For logos, icons, and illustrations made of geometric shapes, SVG (Scalable Vector Graphics) beats all raster formats. It's infinitely scalable, resolution-independent, and typically 5–50× smaller than equivalent PNG for simple graphics. SVG is XML text — gzip-compressible and cacheable. Use SVG wherever you have vector artwork.

Converting Between Formats

The ToollyX Image Converter converts between JPG, PNG, WebP, and BMP in batch. Set the output format, adjust quality, drop your images, and download. All conversion runs in your browser — no uploads. For format-specific compression after conversion, use the Image Compressor to fine-tune file sizes further.