AI Humanizer BenchmarkLeaderboard / Compare / StealthGPT vs UndetectedGPT
Head to head · September 2026 cycle
StealthGPT vs UndetectedGPT
UndetectedGPT finished 13.0 points ahead of StealthGPT in the September 2026 cycle, 84.90 to 71.90, ranking #1 against #7 in a field of 11. UndetectedGPT scored higher on 5 of 7 detectors and 6 of 7 writing categories. StealthGPT came out ahead on Readability (82.7 vs 77.3), Copyleaks (57.6 vs 21.2), Winston AI (62.1 vs 54.4). The bypass-rate gap, 74.6 to 86.3, sits inside both tools' 95% confidence intervals, so treat bypass as a draw.
- Detectors
- 2 – 5
- Categories
- 1 – 6
- Components
- 1 – 4
- Last tested
- 2026-09-03
- Prompts
- 33
- Methodology
- v1.0.0
Score components
What the overall score is made of: bypass rate weighs 42%, meaning preservation 32%, readability 16%, consistency across categories 10%. Output-quality penalties come off the total. How scoring works
CIs overlap marks a gap that sits inside both tools' 95% confidence intervals for bypass rate; it may not survive another cycle.
Detector by detector
Share of each tool's outputs that a detector classified as human-written. UndetectedGPT took 5 of 7.
Writing categories
Category score per writing context: bypass credit only for real rewrites, blended with the category's own meaning preservation and readability. Small categories swing; the prompt count is shown on each row.
Where each one wins
Every measure above that one tool won outright, largest margin first within each group.
StealthGPT
4 wins- Readability Score82.7 vs 77.3
- Copyleaks Detector57.6 vs 21.2
- Winston AI Detector62.1 vs 54.4
- Business email Category81.3 vs 79.7
UndetectedGPT
15 wins- Meaning preservation Score84.8 vs 70.1
- Consistency Score91.5 vs 78.5
- Bypass rate Score86.3 vs 74.6
- Penalties ScoreNone vs −3.0
- Originality.ai Detector79.2 vs 48.2
- QuillBot Detector92.7 vs 66.0
- ZeroGPT Detector85.1 vs 66.5
- Grammarly Detector89.3 vs 77.5
- GPTZero Detector80.0 vs 78.2
- Discussion board Category90.3 vs 57.2
- Application essay Category86.2 vs 66.5
- News article Category85.9 vs 68.8
- Academic essay Category89.2 vs 80.0
- Blog post Category77.6 vs 76.6
- Marketing copy Category85.8 vs 85.0
Questions people ask
Is StealthGPT better than UndetectedGPT?
UndetectedGPT finished 13.0 points ahead of StealthGPT in the September 2026 cycle, 84.90 to 71.90, ranking #1 against #7 in a field of 11. UndetectedGPT scored higher on 5 of 7 detectors and 6 of 7 writing categories. Both tools ran the same 33 prompts, scored by the same 7 detectors, under methodology v1.0.0; every input, output, and verdict is published.
Which bypasses AI detectors better, StealthGPT or UndetectedGPT?
UndetectedGPT posted the higher bypass rate, 86.3 vs 74.6, and scored higher on 5 of 7 detectors. StealthGPT led on Winston AI and Copyleaks; UndetectedGPT led on GPTZero, Originality.ai, ZeroGPT, Grammarly and QuillBot. The overall bypass gap is inside both 95% confidence intervals, so it is not a reliable difference.
Do StealthGPT and UndetectedGPT keep the original meaning?
UndetectedGPT preserved meaning better, 84.8 vs 70.1 on our 0–100 similarity scale. On readability, StealthGPT rated higher, 82.7 vs 77.3. Penalties this cycle: StealthGPT −3.0, UndetectedGPT None.