A JPG quality slider looks simple, but the numbers can be misleading. Quality 80 does not mean the image keeps exactly 80 percent of the original information. Different encoders interpret the scale differently, and the visual result depends heavily on the image content.
Photos with natural texture can tolerate more compression than images with text, gradients or flat color blocks. A landscape at quality 70 may look fine. A screenshot saved as JPG at quality 70 may look broken. The right setting depends on the final use, not a universal rule.
Use 85 as the default starting point
For most website photos, quality 80 to 85 is a sensible starting range. It usually cuts file size significantly while keeping visible artifacts low. This is often enough for blog images, product photos, hero images and social media exports.
Quality 95 is useful when you need a high-quality delivery file, but it can create much larger files with little visible benefit on screen. Quality 50 to 60 is useful for thumbnails, previews and low-priority images where speed matters more than detail.
Compare at the final display size
Do not judge compression by zooming into a photo at 400 percent. Visitors will see the image at its display size. Export two or three versions, place them in the page or app where they will appear, and pick the smallest one that still looks clean.
Keep the original photo separately. If you compress too far and only keep the compressed file, future edits will stack artifacts. The clean workflow is original file, one optimized export, and no repeated JPG saves.