Head to head · September 2026 cycle
SupWriter vs Undetectable.ai
SupWriter finished 1.0 points ahead of Undetectable.ai in the September 2026 cycle, 72.80 to 71.75, ranking #5 against #6 in a field of 14. SupWriter scored higher on 2 of 5 detectors and 3 of 7 writing categories. Undetectable.ai came out ahead on GPTZero (72.4 vs 21.0), readability (61.7 vs 45.7) and Originality.ai (91.7 vs 78.5). The bypass-rate gap, 80.3 to 82.1, sits inside both tools' 95% confidence intervals, so treat bypass as a draw.
- Detectors
- 2 – 3
- Categories
- 3 – 4
- Components
- 1 – 4
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' published 95% confidence intervals for that component; it may not survive another cycle.
Detector by detector
Share of each tool's outputs that a detector classified as human-written. Undetectable.ai took 3 of 5.
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. How category scores work →
Where each one wins
Every measure above that one tool won outright, largest margin first within each group.
SupWriter
6 wins- Penalties Score None vs −6.0
- Copyleaks Detector 85.3 vs 74.3
- Winston AI Detector 81.5 vs 78.9
- News Article Category 81.1 vs 51.8
- Blog Post Category 78.4 vs 57.5
- Marketing Copy Category 81.3 vs 78.4
Undetectable.ai
11 wins- Readability Score 61.7 vs 45.7
- Consistency Score 71.1 vs 64.7
- Meaning preservation Score 82.1 vs 79.0
- Bypass rate Score 82.1 vs 80.3
- GPTZero Detector 72.4 vs 21.0
- Originality.ai Detector 91.7 vs 78.5
- ZeroGPT Detector 80.4 vs 77.9
- Business Email Category 51.0 vs 38.7
- Application Essay Category 73.8 vs 67.1
- Academic Essay Category 86.0 vs 79.7
- and 1 more
Questions people ask
Is SupWriter better than Undetectable.ai?
SupWriter finished 1.0 points ahead of Undetectable.ai in the September 2026 cycle, 72.80 to 71.75, ranking #5 against #6 in a field of 14. SupWriter scored higher on 2 of 5 detectors and 3 of 7 writing categories. Both tools ran the same 33 prompts, scored by the same 5 detectors, under methodology v1.2.0; every input, output and verdict is published.
Which bypasses AI detectors better, SupWriter or Undetectable.ai?
Undetectable.ai posted the higher bypass rate, 82.1 vs 80.3, and scored higher on 3 of 5 detectors. SupWriter led on Copyleaks and Winston AI; Undetectable.ai led on GPTZero, Originality.ai and ZeroGPT. The overall bypass gap is inside both 95% confidence intervals, so it is not a reliable difference.
Do SupWriter and Undetectable.ai keep the original meaning?
Undetectable.ai preserved meaning better, 82.1 vs 79.0 on our 0–100 similarity scale, though the confidence intervals overlap. On readability, Undetectable.ai rated higher, 61.7 vs 45.7. Penalties this cycle: SupWriter None, Undetectable.ai −6.0.