Grok 4.6 (12 August 2026) and GPT-6 Astra (4 September 2026) sit at opposite ends of the price range for frontier-class text models. The gap in capability is smaller than the gap in cost, but it is real and it is concentrated in software engineering.
Published prices and limits
Grok 4.6 is 8.3x cheaper per output token and writes faster. GPT-6 Astra carries twice the context window. Grok's 450,000-token output ceiling is the largest in our tracked catalog by a wide margin, which matters for long generation runs rather than long prompts.
Benchmark results
GPT-6 Astra leads every benchmark both vendors publish. It also publishes far more of them: a complete set across coding, reasoning, agents, writing, chat and vision, where xAI's tables concentrate on knowledge work and leave several categories unreported.
That asymmetry is worth naming. xAI's published results are strongest on knowledge-work evaluations and weakest on pure software engineering, and Grok 4.6 does not publish a Terminal-Bench 4.0 score — the benchmark where the spread between models is widest. A missing result is not a bad result, but it does mean the comparison rests on the benchmarks xAI chose to publish.
Which to pick
If output volume dominates your bill, Grok 4.6 delivers roughly 89% of Astra's DeepSWE score at 12% of the output price. If you are doing repository-scale engineering where Terminal-Bench-style failures are expensive, Astra is the one with the evidence.
