xAI releases Grok 4.6 for long-running agents

xAI released Grok 4.6 on 12 August 2026. The launch positions it for long-running agents and ambitious interactive and visual work rather than as a raw capability increase over Grok 4.5.

Pricing starts at $2 per million input tokens and $6 per million output, with a fast variant at twice the price. Below 200K prompt tokens, cached input is $0.50 per million. It is available in the API and via OpenRouter, Vercel and Cloudflare.

Grok 4.6 posted a GDPval-AA v2 Elo of 1753 and 15.8% on Harvey's Legal Agent Benchmark at launch. Terminal-Bench 3.0 was 26%. On xAI's own ten-row comparison, Claude Fable 5 wins the most rows; Grok is strongest on knowledge work and legal reasoning.

On long agentic tasks the model completed work in roughly 53 turns at $0.84 per task, against Claude Opus 5's 103 turns. Artificial Analysis notes it starts answering later and can cost more per measured task than Grok 4.5 in some conditions.

Nvidia stated Grok 4.6 was trained and runs on GB300 NVL72 with NVLink. xAI did not publish a parameter count in the launch post or API documentation.

Grok 4.7, described by Musk as a 2.1-trillion-parameter successor, remained unreleased as of mid-September after delays attributed to reinforcement-learning tuning, response-length penalties and self-checking. On 13 September Musk named Grok 4.8 as a 2.5-trillion-parameter model on a new C++ stack.

On 24 July Musk said 4.7 would arrive in four weeks; four days later he revised that to a few weeks. On 11 September he said the model needed a few more days of tuning, noting it stopped too early on difficult tasks and did not check its own work rigorously enough. On 14 September he graded it as roughly on par with Opus 5.0 rather than 5.1.

All Grok 4.7 details trace to Musk's posts on X rather than xAI documentation. No context window, pricing, benchmark package or API model ID has been published. Grok 4.6 remains the latest officially available model in the line.

SpaceX, which bought xAI in February 2026, disclosed in its Nasdaq listing filing that the xAI segment lost $2.47bn from operations in the first quarter of 2026 on $818m of revenue. The same filing shows Anthropic paying SpaceX $1.25bn a month for Colossus compute — a rival lab renting the machines.