Grok 4.6 vs GPT-5.6 Sol

Artificial Analysis places Grok 4.6, released August 7, 2026, level with GPT-5.6 Sol and above Kimi K3, third overall on its index. That is the whole reason this comparison is interesting, because the two models are not priced anywhere near each other. Sol charges $5 per million input tokens and $30 per million output. Grok 4.6 charges $2 and $6 for any request under 200,000 tokens, with cached input at $0.50. The catch is the cliff: once a request crosses 200,000 tokens, Grok rates double to $4 input, $1 cached, and $12 output, and the higher tier applies to every token in that request rather than only the overage. Sol has no equivalent step and ships a full 1 million token window against Grok's 500,000. Architecturally Grok 4.6 is the same 1.5 trillion parameter V9 foundation as Grok 4.5 with the entire gain coming from supervised fine-tuning and reinforcement learning, which is xAI's explicit bet that post-training beats parameter count at a fixed latency and cost envelope. It is also why 4.6 should be treated as a checkpoint: xAI has signaled a 2.1 trillion parameter Grok 4.7 within weeks and says it will train from scratch monthly through the end of 2026. Sol is the more conservative choice on ecosystem, tooling, enterprise deployment, and the sheer volume of independent evaluation behind it. Grok is the choice if your prompts stay under 200K and the index parity holds up on your own evals.