Side-by-side technical and economic comparison between xAI's Grok 2 and OpenAI's GPT-5.6 Mini.
• Grok 2: Classified as a Legacy Reference model (Generally Available).
| Metric | Grok 2 | GPT-5.6 Mini | Advantage |
|---|---|---|---|
| Provider Organization | xAI | OpenAI | — |
| Standard Input / 1M | $2.00 | $0.30 | GPT-5.6 Mini (85% lower) |
| Cached Input / 1M | None | $0.03 | GPT-5.6 Mini lower |
| Output / 1M | $10.00 | $1.20 | GPT-5.6 Mini lower |
| Context Window | 128k | 400k | GPT-5.6 Mini (400k) |
| Max Generation Tokens | 8.2k | 16.4k | GPT-5.6 Mini |
| Tokenizer Family | xAI Byte-level BPE (~131k vocabulary) | OpenAI o200k_base (200k vocabulary) | — |
Opt for Grok 2 when your engineering requirements prioritize xAI's ecosystem, specific tokenizer efficiencies (Calibrated xAI Tokenizer (±3%)), or when your expected prompt-to-completion ratios favor its $2/M input rate.
Opt for GPT-5.6 Mini when looking for OpenAI's tooling integration, specific context window depth (400k tokens), or when output generation volume favors its $1.2/M rate.