What is the threshold Google deems content ai written vs not?

What signals does Google use to distinguish well-written AI content from content created by a human writer

Google does not explicitly disclose the “threshold” that distinguishes whether content is AI-written or human-written, because according to Google Search Center, Google focuses on content quality, relevance, and EEAT (experience, expertise, authoritativeness, and trustworthiness), rather than the tools used to create the content. However, Google’s 2025 algorithms (such as “useful content updates”) and spam policies can identify patterns associated with low-quality AI content, especially in YMYL areas such as casinos and cryptocurrencies.