Zerogpt basically looks for statistical fingerprints in your text—stuff like sentence structure, word variety, how “predictable” your word choices are—to guess if it’s AI-generated. The idea is large language models (like GPT-4, etc) tend to use certain phrasing, structure, and even rhythms that are just a little too tidy or predictable for most humans. But (and it’s a BIG but), accuracy is suuuper hit or miss. I’ve had it tell me my totally-off-the-cuff blog post was “potentially AI” and then turn around and say a GPT essay was 100% human. Wild.
I wouldn’t put all your eggs in Zerogpt’s basket. Honestly, sometimes the same text flagged on Zerogpt slides right under the radar with Copyleaks or Originality.ai. If you just want a rough vibe-check, fine, but don’t treat the results as gospel. The main issue: if your writing style is clean, tight, and uses big words (or if you edit your drafts a lot), these detectors get suspicious FAST.
Also, I kinda disagree with @mikeappsreviewer about “sub-50%” meaning you’re safe. I’ve seen stuff under 40% flagged in classrooms and clients FREAK. And using those AI humanizers is a band-aid at best, because half the time they just butcher your voice.
Bottom line: if you’re worried about accuracy, try a few detectors and cross-reference. And if one says “HIGHLY LIKELY AI,” don’t panic—it probably just means you write better than 90% of people online 
.