How much can you compress a photo before it looks bad? More than most people expect — but the honest answer depends on the photo, not just the number on the slider. Here's what actually happens at each stage of compression, so you can judge it for your own photo instead of guessing.
Why the same percentage looks different on different photos
A simple, evenly lit photo — a plain headshot, a product shot on a white background — can be compressed hard with almost no visible change, because there's not much fine detail for the compression to disturb in the first place. A busy, high-detail photo — foliage, fabric texture, a crowd scene — shows compression artifacts sooner, because there's more detail for the algorithm to simplify away. That's why "compress it a lot" is a meaningless instruction without knowing what the photo actually contains.
What to expect at each stage
- Light compression (roughly 20 to 40 percent file size reduction): Effectively invisible on nearly any photo. This is the range most everyday compression — getting under an email or upload limit — actually lands in.
- Moderate compression (40 to 70 percent reduction): Still generally clean on simple photos; on detailed images, close inspection may start to reveal slight softness in fine textures.
- Heavy compression (70 to 85 percent reduction): Visible quality loss becomes likely on most photos — softened detail, mild blockiness around sharp edges, and banding in smooth gradients like skies or skin tones.
- Extreme compression (beyond 85 percent reduction): Quality loss is usually obvious at normal viewing size, not just on close inspection. Worth it only when a strict size limit leaves no other option.
These ranges are general guidance based on typical compression behavior, not a precise measurement — where your specific photo falls depends on its content.
The point where resolution beats quality
Past a certain point, reducing quality further stops being the better tradeoff — a smaller image at higher quality tends to look better than a full-size image compressed hard enough to hit the same file size. That's why a well-built compressor switches strategies partway through: reduce quality first while it's still invisible, then start reducing resolution once quality reduction alone would start looking bad.
Testing this on your own photo
Numbers and percentages only go so far — the fastest way to know how far you can push a specific photo is to actually look at it:
- Drop your photo into the compressor and pick a target size.
- Compare the before/after preview directly, rather than trusting a percentage in the abstract.
- If it looks soft, back off the target slightly — the difference between "just right" and "too far" is often a small size increase, not a dramatic one.
The real answer
There's no single number that applies to every photo. But as a practical rule: most photos tolerate 50 to 70 percent file size reduction with no visible cost, and the honest way to know where yours falls is to look at the actual before/after, not the percentage.