Side-by-side comparison of pricing, 12 benchmarks, and generation speed.
| Metric | Gemini 2.5 Flash Preview (Sep '25) (Reasoning) | GPT-5.4 nano (medium) |
|---|---|---|
| Input ($/M tokens) | $0 | $0.2 |
| Output ($/M tokens) | $0 | $1.25 |
Data from Artificial Analysis API — 12 benchmarks
Gemini 2.5 Flash Preview (Sep '25) (Reasoning) is cheaper overall. Its blended price (3:1 input/output ratio) is $0.00/M tokens vs $0.46/M for GPT-5.4 nano (medium).
Gemini 2.5 Flash Preview (Sep '25) (Reasoning) wins 6 out of 12 benchmarks compared to 5 for GPT-5.4 nano (medium). See the detailed benchmark chart above for per-category results.
GPT-5.4 nano (medium) generates tokens faster at 171 tok/s vs 0 tok/s. Gemini 2.5 Flash Preview (Sep '25) (Reasoning) also has lower time-to-first-token (0.00s vs 2.38s).
Choose based on your priorities: Gemini 2.5 Flash Preview (Sep '25) (Reasoning) for lower cost, Gemini 2.5 Flash Preview (Sep '25) (Reasoning) for stronger benchmark performance, and GPT-5.4 nano (medium) for faster generation. For latency-sensitive apps, check the TTFT comparison above.