1 in 4 long social media posts is now written by AI, LinkedIn tops the list

A new analysis by Pangram shows that one out of every four long posts (over 250 words) on social media is written by AI. LinkedIn has the highest share, with 41% of its long posts flagged as AI-written. Though LinkedIn only made up about a third of all scanned posts, it produced nearly two-thirds of the AI content.

On X, almost half of long posts were fully or partially AI-generated. Substack had the lowest AI rate at about 10%. Reddit replies were almost entirely human-written (98%), but standalone posts showed more AI text.

The data came from Pangram's Chrome extension, which scanned over 1 million posts across five platforms from April to June 2026. Its detection model Pangram 3 has a false positive rate of just 0.01%, but the real AI share might be even higher. LinkedIn has started cracking down on AI-generated posts.