JPEG Quality Science · Image Compression
CompressJPEG Doesn't Tell You What Quality It Uses. We Measured It. Here's What That Means for Your Images.
CompressJPEG.com (by Tinify) is one of the most-used image compression tools online. It works — but it applies a fixed automated quality setting, takes your image to their servers, and gives you back a JPEG. No quality control. No format conversion. No target file size. Here's the science behind why that matters.
JPEG Quality Explorer
Drag to explore quality vs. file size
Based on a typical 18 MP DSLR photo (original ~8 MB). CompressJPEG uses approximately Q75 internally.
Standard web quality. Artifacts visible only on close inspection. Recommended range.
Tinify's algorithm targets ~~620 KB for this image type. You cannot adjust this. No slider, no target KB mode.
Q values are JPEG quantization quality (libjpeg scale). "Approx size" is illustrative; actual results depend on image content.
The three things CompressJPEG can't do
When CompressJPEG is genuinely the right tool
CompressJPEG's 20-image free batch is straightforward to use. If you're a non-technical user who has 15 JPEG photos from a family event and wants to email them — upload, compress, download the ZIP, done. The output quality is good. Tinify's algorithm is well-regarded.
For social media content creators who always output JPEG and have no need for format conversion or size targeting, CompressJPEG is fine. The tool is simple and trustworthy for casual use.
The moment you need quality control, target file sizes, format conversion, or local processing of sensitive images — it's the wrong tool.
Verified specs (Sept 2026)
Need quality control, AVIF, or a target KB output?