Codex Accounts for 99.8% of OpenAI Internal Token Output as of June 2026

According to an OpenAI economics paper titled 'The Shift to Agentic AI: Evidence from Codex,' as of June 2026, the AI platform Codex has become dominant across OpenAI's operations. Internal staff members generate tokens primarily through Codex, with 99.8% of weekly token output sourced from the platform. Engineers show 99% Codex token usage, while non-technical employees in legal and recruiting roles exceed 85% usage. Approximately 28.6% of staff manage five or more AI agents simultaneously, with heavy users logging over 71 cumulative hours daily.

External adoption is accelerating similarly. Sampling of individual users shows task submissions estimated to exceed 8 hours of human work rising from 2.1% to 25.6% within six months. Since August 2025, external individual and organizational non-developer weekly active users have surged 137 times and 189 times respectively. Codex Skills usage rate across active users increased from 5.4% to 26.6% in three months.