Compression Ratio
The ratio between original and compressed data sizes. Higher ratios yield smaller files but may introduce quality loss in lossy formats.
Compression ratio expresses the relationship between original and compressed data sizes. A 10 MB image compressed to 1 MB achieves a 10:1 ratio (90% reduction). For web delivery, file size directly impacts loading speed, making compression ratio selection critical.
In lossy compression formats like JPEG, the quality parameter (1-100) controls the ratio. Quality 80 typically balances visual fidelity with size reduction, while values below 60 produce noticeable block artifacts. Lossless formats like PNG achieve ratios dependent on image content, with flat-color regions compressing more efficiently.
The image compression tool provides a quality slider for real-time ratio adjustment with preview. Modern formats like WebP and AVIF achieve 25-50% smaller files than JPEG at equivalent visual quality.