GPT-6 Astra vs Kimi K3.1 Pro

Where it leads

• Higher Arena WebDev score, 1773 Elo vs 1695 Elo

Best for

• Frontier reasoning and agentic evaluations where deep-context retrieval accuracy is the binding constraint
• Workloads that can be kept under the long-context threshold, where the effective rate stays at $10 / $50

Watch out for

• Long-context billing is a cliff, not a taper: a request over the long-context threshold is rebilled in full at $20 per million input and $75 per million output, so a prompt that crosses it costs roughly double
• GPT-6 Astra is the first publicly released model OpenAI classifies as crossing the Critical cybersecurity threshold under its own Preparedness Framework, which carries additional deployment safeguards
• Vendor-reported benchmark figures come from OpenAI’s own launch material and its own harness; they are not independently reproduced here

Where it leads

• Lower input and output prices, $2 and $10 vs $10 and $50 per 1M tokens
• Accepts video input
• Cheaper cached input, $0.20 vs $1 per 1M tokens

Best for

• Long-horizon coding and agent work at mid-tier prices
• Long documents, images and video in one 1M-token context

Watch out for

• Thinking is always on: reasoning effort runs low, high or max, and max is the default
• The Highspeed endpoint, two to three times faster by Moonshot's account, costs twice as much at $4 input and $20 output per 1M tokens
• Weights are promised by 4 November 2026 and were not out on 3 November; Epoch AI and Arena Text have not scored it yet