Progressive JPEG vs Baseline JPEG: What's the Difference?

JPEG has two encoding modes: baseline (standard, top-to-bottom decoding) and progressive (multiple passes, blurry-to-sharp). Both are valid; choose based on your content and network.

Baseline JPEG

Decodes top-to-bottom as data arrives. User sees image forming from top. File size is slightly smaller. Default in most tools.

Progressive JPEG

Stores image in multiple passes (usually 4–5). First pass is 1/8 resolution (blurry). Each pass adds detail. File size is 5–10% larger.

Perceived Performance

Progressive JPEG feels faster on slow networks. User sees blurry image quickly, then sharpens. Reduces perceived waiting time.

File Size Impact

Progressive: 5–10% file size increase. On a 100KB JPEG, that is 5–10KB extra. Usually not significant enough to matter.

Browser Support

All browsers support both. Progressive works everywhere. No compatibility issues.

When to Use Progressive

Hero images, above-the-fold photos on slow networks. User experience benefit is real, file size cost is minimal.

When Baseline Is Fine

Thumbnails, below-the-fold images. Fast networks (5G, fiber). User will not notice.

CPU Cost

Progressive requires slightly more CPU to decode multiple passes. On modern devices, negligible. On very old phones, baseline might be faster.

Recommendation

Use progressive JPEG by default. File size cost is worth perceived performance gain. WebP and AVIF make this less critical, but progressive is still good practice.

Tool Support

Photoshop: File > Export > JPEG > progressive checkbox. Exiftool: automatic detection. QuickConvert defaults to progressive.