# AI-generated web text

Using EditLens and Pangram to label Common Crawl web data from 2021 to 2026, the authors find that 27.5% of tokens passing FineWeb quality filtering in June 2026 are AI-generated, rising to 31.1% in August, and by pretraining 800 models from 19.9M to 973M parameters while varying the ratio of added AI to human tokens they fit a new scaling law with separate benefit and harm terms: AI tokens lower loss for data-starved models before saturating and reversing into harm, raise loss almost immediately for Chinchilla-optimal models, and the law predicts held-out sizes with lower error than eleven existing laws, implying that training at August 2026's AI share takes 1.6x the compute.

Using EditLens and Pangram to label Common Crawl web data from 2021 to 2026, the authors find that 27.5% of tokens passing FineWeb quality filtering in June 2026 are AI-generated, rising to 31.1% in August, and by pretraining 800 models from 19.9M to 973M parameters while varying the ratio of added AI to human tokens they fit a new scaling law with separate benefit and harm terms: AI tokens lower loss for data-starved models before saturating and reversing into harm, raise loss almost immediately for Chinchilla-optimal models, and the law predicts held-out sizes with lower error than eleven existing laws, implying that training at August 2026's AI share takes 1.6x the compute.