Compress an image too aggressively and it comes back visibly worse — blotchy gradients, blocky edges around text or hard lines, a general "smeared" look. That's not a bug in the compressor; it's exactly what a quality setting pushed too low is supposed to do, trading visual fidelity for file size on purpose. The fix is almost always to dial the setting back, not to avoid compression altogether.
Quality is a trade-off dial, not a pass/fail setting
A compression quality setting (commonly a 1-100 or 10-95 scale) controls how much visual detail gets sacrificed for a smaller file. High quality settings keep almost all the original detail and shrink the file only modestly. Low quality settings throw away much more detail — smoothing out subtle color gradients, simplifying fine texture — in exchange for a dramatically smaller file. Neither end is "correct"; the right value depends entirely on what the image is being used for.
Where the setting actually matters
- 70-85 is a good default for most photos going on a website or in a document — visually close to indistinguishable from the original at a meaningfully smaller size.
- 40-60 is fine for thumbnails, previews, or drafts where the image will be shown small or isn't the main focus — some compression is visible up close, but rarely noticed at a glance or at a smaller display size.
- Below 30-40 is where artifacts start becoming obvious even at normal viewing size — blocky patches, banding in gradients, blurred fine detail. Worth it only when file size is genuinely more important than appearance.
Sometimes compression genuinely can't help
Not every image has room to shrink safely. An image that's already been compressed once (a JPEG re-saved as another JPEG, for instance) has less redundant data left to squeeze out — compressing it again at a similar quality level may barely reduce the size at all, because there's nothing left to trade away that wasn't already traded away the first time. If a compressed result comes back the same size as the original, that's the compressor correctly recognizing there was nothing more to gain — not a sign that something went wrong.
Using the tool
Our Image Compressor lets you set the exact quality level yourself (10-95) rather than picking a fixed "high/medium/low" preset, and if your chosen quality would somehow produce a larger file than the original, it returns the original unchanged instead — you'll never end up worse off than when you started.
Try it here: Image Compressor.