AI Humanizer Benchmark

AI Humanizer Benchmark is an independent monthly testing site that ranks 11 AI humanizer tools by running them through 7 AI detectors, including GPTZero, Originality.ai, and Copyleaks. Each tool rewrites the same 33 texts on default settings, and scores are based on bypass rate, meaning preservation, and readability. It is for anyone who wants to know which humanizers actually work without ruining the text, from students to marketers. All raw data is public on GitHub.

How it works

Each month, the benchmark generates new AI-written texts in 7 writing categories, from essays to marketing copy. Every humanizer rewrites the same 33 texts through API calls on default settings, not tuned setups. The rewrites are then scored by 7 commercial detectors, and semantic similarity measures meaning preservation while a language model rates readability. All inputs, outputs, and detector verdicts are published on GitHub, so anyone can recompute the results.

Scoring formula

The overall score out of 100 combines bypass rate (42%), meaning preservation (32%), readability (16%), and consistency across writing types (10%). Penalties subtract points for issues like identical output, refusals, meaning drift, and length inflation or deflation. The maximum total penalty is -50.0. This means a tool that beats detectors but wrecks the text does not rank high.

Detector panel

The detector panel includes GPTZero, Originality.ai, Copyleaks, Winston AI, ZeroGPT, QuillBot, and Grammarly. Each detector's result is converted to a common 0-1 scale, and the bypass result is the median across all 7, so no single detector outweighs the others. Each detector has its own page ranking humanizers by bypass rate against that detector alone.

Use-case rankings

The site offers use-case views that reweight or filter results, such as best for essays, SEO, marketing, academic writing, or students. There are also pages for best for quality, meaning preservation, readability, and bypass rate. A 'best for free' view ranks only humanizers with a free tier. These views help users find the right tool for their specific needs.