Lossy vs Lossless Compression: What Changes and When to Use Each

Quick answer

Lossy compression reduces file size by removing some image data. Lossless compression reduces file size without losing any data. Use lossy for photos and web performance, and use lossless for graphics, text, or assets that need perfect detail.

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What is lossy compression?

Lossy compression removes some image information to shrink file size. The goal is to remove detail that is less noticeable while keeping the image visually accurate. This is why JPEG is popular for photos and why WebP can create small, high-quality images for the web.

Pros: much smaller file sizes, faster loading.
Cons: detail is permanently removed, repeated saves degrade quality.
Best for: photos, backgrounds, hero images, and large galleries.

What is lossless compression?

Lossless compression keeps every pixel intact. It reduces file size by finding patterns and storing them more efficiently. PNG is the most common lossless format, and WebP also supports lossless mode.

Pros: no quality loss, perfect for crisp edges.
Cons: larger file sizes compared to lossy formats.
Best for: logos, UI elements, screenshots, and diagrams.

How to choose between lossy and lossless

If the image is a photo: choose lossy, start at quality 80.
If the image has text or sharp edges: choose lossless.
If you need transparency: use lossless PNG or WebP.
If you need the smallest file: use lossy WebP and compare.

Signs that lossy compression is too aggressive

Blocky artifacts around edges.
Banding in gradients and skies.
Text or UI elements that look fuzzy.

If you see these artifacts, increase quality or switch to lossless.

Workflow tips to protect quality

Keep an original file and export new versions as needed.
Avoid repeated re-saving of JPEG files.
Resize before compressing to avoid extra artifacts.