JPG, PNG, and WebP: When to Use Each Image Format

Raster formats are engineering trade-offs

Every image format optimizes for different constraints. JPEG minimizes size for continuous-tone photos using lossy DCT compression. PNG preserves exact pixels with lossless DEFLATE, supporting alpha transparency. WebP combines lossy and lossless modes with modern entropy coding, often beating JPEG and PNG size at equal perceived quality on supported platforms.

Choosing wrong formats produces either bloated pages or ugly artifacts. A screenshot saved as JPEG gains ringing around text; a photograph saved as PNG may be ten times larger than necessary. Conversion tools should be guided by content class, not habit.

Decision matrix by content type

Use JPEG for camera photos, textures, and gradients without transparency. Use PNG for UI captures, line art, logos needing alpha, and small palettes. Use WebP for web delivery when analytics show sufficient browser support; keep JPEG duplicates for legacy email. Avoid GIF for still photos; use short WebM or MP4 for motion.

When converting between formats, never upsample a low-resolution JPEG to PNG expecting quality gains—you only enlarge artifacts. Start from the highest quality source available, convert once, and document the preset for your team.

Accessibility and metadata

Raster images in articles need alt text in HTML; format choice does not replace accessibility. Strip location EXIF from user-generated uploads when publishing. Color profiles may shift between formats; verify brand colors on calibrated monitors for packaging shots.