Image compression depends on dimensions, format, quality and picture content. There is no universal “80% smaller with no loss” setting. Use the Image Compressor and Format Converter to compare outputs from your actual image.
A useful comparison workflow
- Keep an original and note its pixel dimensions and file size.
- Resize to the largest dimensions the destination needs, allowing for high-density displays where appropriate.
- Export a candidate. Inspect it at the intended display size and 100% zoom. Check small text, gradients, hair, sharp edges and transparent boundaries.
- Compare bytes using (original − output) / original × 100. Reducing 800,000 bytes to 320,000 bytes is a 60% reduction. This is an arithmetic example, not a universal benchmark.
- Open the final download in the application where it will be used.
Format choices
JPEG is common for photographs without transparency. PNG supports lossless graphics and transparency but can be large for photographs. WebP supports lossy and lossless forms and is worth comparing. This converter exports WebP, PNG or JPEG, not GIF or AVIF. Canvas conversion creates a still image and does not preserve animation.
Quality settings have limits
A quality setting is an encoder input, not a percentage of visual fidelity. Two formats or browsers may produce different files at the same setting. Repeated lossy recompression can accumulate artifacts; start from the original for each comparison.
Consult the MDN image format guide for format characteristics. Choose the measured file and visible result, not a promised PageSpeed score.