OpenAI officially released GPT-5.4 mini and GPT-5.4 nano on March 17, 2026, calling them its “most capable small models yet.” Both are designed for high-volume, latency-sensitive workloads where the flagship GPT-5.4 is simply overkill — and priced accordingly.

GPT-5.4 Mini vs Nano: Key Specs at a Glance

Feature	GPT-5.4 Mini	GPT-5.4 Nano
Speed	2x faster than GPT-5 mini	Fastest in the GPT-5.4 family
Input Pricing	$0.75 / 1M tokens	$0.20 / 1M tokens
Output Pricing	$4.50 / 1M tokens	$1.25 / 1M tokens
Context Window	400K tokens	400K tokens
SWE-Bench Pro	54.4%	Nano-tier (below mini)
OSWorld-Verified	72.1%	39%
Availability	API, Codex, ChatGPT	API only
Best For	Coding, agents, computer use	Classification, extraction, ranking

What Makes These Models Worth Paying Attention To

The benchmark gap between mini and the full GPT-5.4 is smaller than you’d expect. On SWE-Bench Pro — a rigorous coding benchmark — mini scores 54.4% against the flagship’s 57.7%. On OSWorld-Verified, which tests computer use via screenshot interpretation, mini reaches 72.1% versus the full model’s 75%. Those are narrow margins at a fraction of the cost, and for most real-world coding tasks the difference won’t be perceptible in the output.

The nano model tells a different story — it’s not trying to compete on reasoning depth. Nano is the smallest, cheapest option in the GPT-5.4 family, and OpenAI recommends it for classification, data extraction, ranking, and coding subagents that handle simpler supporting tasks. At $0.20 per million input tokens, it’s cheaper than Google’s Gemini Flash-Lite — a meaningful competitive edge for developers processing enormous volumes of data.

The Bigger Picture: A New Way to Build AI Systems

What OpenAI is really selling here is an architecture pattern. Rather than running one large model for everything, developers can now have GPT-5.4 handle planning and complex reasoning while mini or nano subagents execute narrow tasks in parallel — codebase search, file review, document processing. In Codex, mini consumes only 30% of the GPT-5.4 quota, making this kind of delegation financially sensible at scale.

GPT-5.4 mini is live today in the API, Codex, and ChatGPT. Free and Go users on ChatGPT can access it through the Thinking feature. GPT-5.4 nano is API-only for now, clearly positioned as developer infrastructure rather than a consumer product.

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