gpt-5-4-mini is the small-mid GPT-5. It keeps the GPT-5 reasoning capability but at roughly one-third the per-token cost of gpt-5-4. The right default for high-volume traffic where you want better-than-Haiku quality without paying flagship rates.
Pricing: 4.50 / 1M output, $0.075 / 1M cache read — see the rate card.
Protocols
Quickstart
Capabilities
When to use
- High-volume classification, routing, structured extraction — anywhere you’d use Haiku for cost but want GPT-flavored reasoning.
- Short-prompt agent loops — tool-use chains where each step is small and the gate is throughput.
- Cheaper Codex-style via Responses API at
reasoning_effort: "low".
- Hard reasoning that benefits from
reasoning_effort: "high"— go togpt-5-4orgpt-5-5. - Web search needed — only
gpt-5-4and up have it.