Side-by-side technical and economic comparison between OpenAI's GPT-5.6 Terra and xAI's Grok 4.6.
| Metric | GPT-5.6 Terra | Grok 4.6 | Advantage |
|---|---|---|---|
| Provider Organization | OpenAI | xAI | — |
| Standard Input / 1M | $2.00 | $2.00 | Identical |
| Cached Input / 1M | $0.20 | $0.50 | GPT-5.6 Terra lower |
| Output / 1M | $12.00 | $6.00 | Grok 4.6 lower |
| Context Window | 1.05M | 500k | GPT-5.6 Terra (1.05M) |
| Max Generation Tokens | 16.4k | 128k | Grok 4.6 |
| Tokenizer Family | OpenAI o200k_base (200k vocabulary) | xAI Byte-level BPE (~131k vocabulary) | — |
| Workload (per month) | GPT-5.6 Terra | Grok 4.6 |
|---|---|---|
| Chatbot10k requests · 500 in / 200 out | $34.00 | $22.00 |
| RAG app100k requests · 8,000 in / 1,200 out | $3,040.00 | $2,320.00 |
| Coding agent100k requests · 12,000 in / 2,000 out | $4,800.00 | $3,600.00 |
Standard rates, no caching or batch discounts. Model your own numbers below.
Opt for GPT-5.6 Terra when your engineering requirements prioritize OpenAI's ecosystem, specific tokenizer efficiencies (Exact BPE (o200k_base)), or when your expected prompt-to-completion ratios favor its $2/M input rate.
Opt for Grok 4.6 when looking for xAI's tooling integration, specific context window depth (500k tokens), or when output generation volume favors its $6/M rate.
At a typical 3:1 input-to-output token mix, Grok 4.6 is about 33% cheaper than GPT-5.6 Terra. GPT-5.6 Terra costs $2 per 1M input and $12 per 1M output tokens; Grok 4.6 costs $2 and $6.
GPT-5.6 Terra has the larger context window: 1.05M tokens vs 500k.
GPT-5.6 Terra: yes, cached input costs $0.2/1M. Grok 4.6: yes, cached input costs $0.5/1M.