Pangram Labs released Pangram 4, an AI text classifier that detects whether text was written by humans or AI systems. The model achieves 99.16% accuracy and can now identify mixed human-AI writing and fine-grained edits better than its predecessor.

• AUROC of 0.9916 with 0.0041% false positive rate and 0.3396% false negative rate
• Can distinguish fine-grained edits and detect interleaved AI assistance in co-authored text
• Shows improved robustness to adversarial attacks and better generalization to out-of-distribution data

Pangram 4 is a new AI detector that’s six times larger than version 3, cutting its false positive rate to 0.0041% and its false negative rate to 0.3396%. The launch also brings per-100-word billing, expanded scan volumes, free image scans, and a two-year overlap with Pangram 3 until its September 2026 deprecation.

• Pangram 4 is six times larger than Pangram 3, cutting false positives to 0.0041% (1 in 24,000 docs) and false negatives from 1.99% to 0.3396%
• It detects AI-humanized text with 98.83% accuracy across 13 commercial humanizer tools, and keeps false negatives under 0.7% across every major model family
• Pricing switches from rounding up to 1,000 words to per-100-word billing, with Individual plans getting 300,000 words/100 image scans monthly and Pro plans 1.5 million words/500 image scans, at no price increase
• Pangram 3 stays available until September 30, 2026, but Pangram 4 must be explicitly selected to be used