AI Detection Benchmark
Systems label private pre-2022 human documents and AI rewrites of them as human or AI written. Both LLMs and commercial detectors are scored by balanced accuracy.
Published 2026-09-30. Claude Opus 5.5 led at 98.38% balanced accuracy, ahead of GPTZero, Pangram and other detectors.
- Level
- Expert Specialists with years of training, often over hours of work
- Scored
- Checked automatically A program checks the result against an answer key, unit tests or the expected final state.
- Answers
- Multiple choice
Claude Opus 5.5 leads with 98.4%
Best score per entry from the benchmark's own leaderboard, read on 2 Nov 2026. Where a model ran with several settings or harnesses, we keep its best. Names in gray aren't in our model list: fine-tunes, agent systems, products and older models. They don't count toward leaders.
- 1 Claude Opus 5.5 98.4%
- 2 GPT-6 Astra 95.8%
- 3 detector/originality 94.1%
- 4 detector/pangram 93.9%
- 5 detector/gptzero 78.1%
- 6 detector/sapling 77.5%
- 7
DeepSeek V4.1 Flash 65.4% - 8 detector/copyleaks 64.6%
| # | Entry | Score | Setting | Date | Source |
|---|---|---|---|---|---|
| 1 | Claude Opus 5.5 | 98.4% | Sep 2026 | Official leaderboard | |
| 2 | GPT-6 Astra | 95.8% | Sep 2026 | Official leaderboard | |
| 3 | detector/originality | 94.1% | Official leaderboard | ||
| 4 | detector/pangram | 93.9% | Official leaderboard | ||
| 5 | detector/gptzero | 78.1% | Official leaderboard | ||
| 6 | detector/sapling | 77.5% | Official leaderboard | ||
| 7 | DeepSeek V4.1 Flash | 65.4% | Sep 2026 | Official leaderboard | |
| 8 | detector/copyleaks | 64.6% | Official leaderboard |
2 models have held number one since its release in Sep 2026
Lab claims count from the day the card came out, independent runs from the model’s release.
The best score passed 85% in Sep 2026
All the scores we have, one dot each, so a model tested at several settings appears more than once.
No lab model card reports it yet
We read the headline results of 479 launch posts from 51 labs, and none of them list this benchmark.
More in Writing and taste
- Design Bench (Moonshot) In use Models make graphic designs from direct prompts or few-shot reference images. An automated grader rates the results as Elo scores. Kimi K3.1 Pro 957
- WritingBench Fading Models complete 1,000 real-world writing requests across 6 domains and 100 subdomains. A judge model scores each reply on five query-specific criteria. GPT-5 83.9
- Creative Writing (MiniMax in-house) Only in system cards Models write creative pieces for real Hailuo AI user requests. Automatic assessments score the writing.
MiniMax-Text-01 81.3% - DeepSeek Chinese functional writing evaluation Only in system cards Models answer 3,170 everyday Chinese writing prompts such as reports, emails and speeches. Pairwise judging against a baseline model gives a win rate. DeepSeek-V4-Pro 62.6%
- Slide generation human evaluation (Z.ai) Only in system cards People compare HTML slide decks from two models on content, layout and visual quality. Metric is overall win rate. GLM-5 67.5%
- Task-dependent output homogenization evaluation Only in system cards Models answer prompts several times. A judge scores functional diversity where it is wanted and consistency where one answer is right.
Muse Spark 0.21