Quickstart

Install imagekbreducer and compress your first file.

Run it once, no install

npx imagekbreducer compress photo.jpg --to 50kb

This writes photo-compressed.jpg next to photo.jpg — it never overwrites your original (see Output files) — and prints a one-line summary to stderr:

photo.jpg → photo-compressed.jpg  3.1 MB → 49.8 KB (98% smaller)

ikb is a shorter alias for the same binary:

npx ikb compress photo.jpg --to 50kb

Install it for repeated use

npm install -g imagekbreducer

imagekbreducer compress photo.jpg --to 50kb
ikb compress photo.jpg --to 50kb

Requires Node 22 or later.

What just happened

--to 50kb parses through the same 1024-based size parser the website uses: 50kb is 51,200 bytes, not 50,000. The tool searches encoder quality (and, unless you pass --no-downscale, pixel dimensions) for the highest-quality file that lands at or under that byte count — never over it, and never a fixed quality that might miss high.

If 50 KB isn’t reachable at all (a --rect-cropped icon can’t be un-cropped, a --no-downscale flag pins the dimensions too high for the format’s own floor), the tool doesn’t fail silently or crash: it exits with a specific code, explains why on stderr, and tells you exactly which flag would fix it. See Exit codes.

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