GPT-5.4 Mini Hits ChatGPT Free/Go — Efficiency Tier, Lab Benches
OpenAI put GPT-5.4 mini in ChatGPT Thinking for Free and Go users (March 18), following the March 17 mini/nano announcement. API: $0.75/$4.50 per 1M in/out, 400k context. Mini lab benches (xhigh): SWE-Bench Pro 54.4%, OSWorld-Verified 72.1%, GPQA Diamond 88.0% — vendor numbers; also rate-limit fallback for higher tiers.
Flagship releases get the headlines; mini is how OpenAI fills Free/Go and rate-limit gaps. The trade: most of the 5.4 coding/reasoning story at lower latency and cost — lab benches still OpenAI’s.
OpenAI documented the GPT-5.4 mini ChatGPT rollout in March 18 release notes to Free and Go users via the Thinking option (+ menu). The March 17 launch post introduced mini across API, Codex and ChatGPT, with nano API-only; the GPT-5.4 family (Thinking/Pro) launched March 5. Mini targets responsive coding assistants, subagents, computer-use agents, and multimodal apps; also acts as rate-limit fallback for GPT-5.4 Thinking on higher tiers. Nano remains API-only at lower pricing.
| Claim (OpenAI, mini at xhigh) | Figure |
|---|---|
| SWE-Bench Pro (Public) | 54.4% |
| OSWorld-Verified | 72.1% |
| GPQA Diamond | 88.0% |
| API price | $0.75 / $4.50 per 1M in/out |
| Context | 400k |
| I/O | Text/image; tools, function calling, web/file search, computer use, skills |
Claims vs checks#
Availability and pricing are OpenAI primary (blog March 17; Help Center release notes March 18). Benchmarks are vendor-reported at the stated effort levels; they do not establish an independent Artificial Analysis or Arena ranking.
Limits#
- Free/Go Thinking quotas still apply.
- Effort-skewed benches are not default-chat Elo.
- Mini and Nano have different economics.
Correction (October 14, 2026): Clarified that nano was API-only, specified xhigh for the cited mini results, and distinguished the March 17 announcement from March 18 release notes.