Side-by-side comparison of pricing, 12 benchmarks, and generation speed.
| Metric | GPT-5.5 (high) | Llama 3.1 Instruct 405B |
|---|---|---|
| Input ($/M tokens) | $5 | $2.75 |
| Output ($/M tokens) | $30 | $6.5 |
Data from Artificial Analysis API — 12 benchmarks
Llama 3.1 Instruct 405B is cheaper overall. Its blended price (3:1 input/output ratio) is $3.69/M tokens vs $11.25/M for GPT-5.5 (high).
GPT-5.5 (high) wins 7 out of 12 benchmarks compared to 5 for Llama 3.1 Instruct 405B. See the detailed benchmark chart above for per-category results.
Llama 3.1 Instruct 405B generates tokens faster at 31 tok/s vs 0 tok/s. GPT-5.5 (high) also has lower time-to-first-token (0.00s vs 0.70s).
Choose based on your priorities: Llama 3.1 Instruct 405B for lower cost, GPT-5.5 (high) for stronger benchmark performance, and Llama 3.1 Instruct 405B for faster generation. For latency-sensitive apps, check the TTFT comparison above.