OpenAI announced on March 18, 2026 that GPT-5.4 Mini and Nano are now available across all ChatGPT tiers, including the free plan. Free and Go users can access GPT-5.4 Mini through the Thinking feature in ChatGPT's plus menu, while paid users receive it as a rate limit fallback when GPT-5.4 Thinking hits capacity. The Nano model is available through the API only.
GPT-5.4 Mini represents a significant performance leap over GPT-5 Mini, with improvements across coding, reasoning, multimodal understanding, and tool use, while running more than twice as fast. OpenAI says the model approaches the performance of the full GPT-5.4 on several benchmarks, including SWE-Bench Pro and OSWorld-Verified, making it a compelling option for developers looking for capable but cost-efficient inference.
The move reflects OpenAI's strategy to keep free-tier users competitive as Anthropic and Google aggressively expand their own offerings. By making its latest architecture accessible at every price point, OpenAI aims to retain the broad user base that made ChatGPT the default AI assistant for millions of users.
For developers, both models are now live in the OpenAI API and Codex at substantially lower price points than GPT-5.4, making them practical for production workloads where the full model would be cost-prohibitive.