The Core Difference: Lossy vs. Lossless
JPG uses lossy compression. When you save a JPG, some image data is permanently discarded to reduce file size. The loss is calculated to be imperceptible at typical quality settings, but it accumulates if you re-save the same JPG multiple times. PNG uses lossless compression. Every pixel is preserved exactly as recorded. No data is lost regardless of how many times you save the file. This makes PNG larger in file size than JPG for equivalent photographic content, but it is the only correct choice when perfect reproduction is required.
When to Use JPG
Use JPG for photographs, product images, food photos, landscapes, and any image where the content is complex, colorful, and photographic. JPG handles gradients and continuous tonal variation well. The slightly lossy nature of JPG is invisible for photos when viewed at normal sizes.
- Photographs and camera images
- Product photos for e-commerce
- Food, travel, and lifestyle imagery
- Any image where transparency is not needed
When to Use PNG
Use PNG when the image contains sharp edges, text, line art, or requires a transparent background. These are all cases where even minor compression artifacts in JPG are immediately visible.
- Logos and brand assets
- Icons and UI graphics
- Screenshots and screen recordings
- Images with transparent or see-through backgrounds
- Diagrams, charts, and illustrations with text labels
File Size Comparison
A typical photograph saved as JPG at 80% quality might be 200KB. The same image saved as PNG might be 1.5-3MB — 7 to 15 times larger. For web use, this directly affects page load speed. Conversely, a simple logo saved as JPG might have compression artifacts along the edges of the logo shape. The same logo saved as PNG is perfectly sharp at any size and may actually be smaller because the PNG compression algorithm handles flat colors and simple shapes efficiently.
What About WebP?
WebP is a newer format developed by Google that combines the best of both worlds. It supports lossless compression (like PNG) and transparency (like PNG), but also delivers lossy compression that produces smaller files than JPG. For websites, WebP is the best default choice. It replaces both JPG and PNG in most web contexts. The Image Converter tool can convert any JPG or PNG to WebP for immediate file size savings.