The quality slider controls the trade-off between file size and visual fidelity — but how it behaves depends on which format you've chosen.
How compression actually affects each format
PNG is lossless — there's no quality slider effect on visual fidelity at all, since PNG doesn't discard image data the way JPG does. What varies is compression effort, which affects file size without ever affecting what the image looks like.
JPG is where the slider matters most. High quality keeps detail but produces a larger file; low quality shrinks the file significantly but introduces visible blockiness, especially around sharp edges and text — exactly the content this tool is most often used to capture. Below roughly 70% quality, artifacts usually become noticeable.
WebP sits in between — its compression is more efficient than JPG's at equivalent visual quality, so you can typically drop the quality setting further before artifacts become visible, for a genuinely smaller file at the same perceived sharpness.
Picking a setting
- Sharing a screenshot for someone to read — prioritize quality (90%+, or just use PNG) over file size.
- Embedding many images in a document with a size limit — JPG or WebP at 70–85% is usually indistinguishable from full quality at a much smaller size.
- Archiving for reference, size doesn't matter — PNG, no compromise needed.
Judge it visually, not just by the number
The percentage itself isn't a universal standard between formats or even between different images — the preview updates live as you adjust the slider, so the reliable approach is watching the preview rather than targeting a specific number. If in doubt, see our format selection guide for which format to start from before fine-tuning quality.