Grok 4.6 Ships: SpaceXAI's 500K-Context Model Matches GPT-5.6 Sol at 50%+ Lower Price
What happened. SpaceXAI (formerly xAI) released Grok 4.6 on August 12, 2026, positioning it for long-running agents and ambitious interactive and visual work. API pricing: $2 per 1M input tokens and $6 per 1M output tokens, with a fast variant at 2x. Artificial Analysis lists a 500,000-token context window and scores the model 61 on its Intelligence Index — matching GPT-5.6 Sol (max) at 61.
The pricing story. Against GPT-5.6 Sol's current promotional pricing ($4/$20 per 1M tokens, through at least Nov 21, 2026 — OpenAI cut Sol by 20%+ on Aug 21, 2026), Grok 4.6 is 50%+ cheaper on input. On output tokens — the dimension that dominates cost in reasoning-heavy agent workloads — $6 vs $20 works out to 70% cheaper. Cache hits run $0.50 per 1M tokens (Artificial Analysis). Note: Sol's $4/$20 rate is promotional — if it reverts to $5/$30 after November 21, 2026, Grok's input advantage widens back to 60%+ and output to 80%. The AI agency cost calculator now models Grok 4.6 with this verified pricing.
Why agent builders should care
- A 500K context window lets a single agent hold a large codebase, an extended session history, or a multi-hour research loop in context.
- Frontier-level intelligence at a lower output-token price makes Grok 4.6 a credible default for agent-heavy builds — and a concrete data point in any GPT-5.6 Sol-priced quote conversation.
- It's available now in Cursor, Grok Build, the SpaceXAI API, OpenRouter, Vercel, and Cloudflare. Cursor and Grok Build include 2x usage for the first week.
What to do
Re-baseline the model line in your agency cost estimates. Run the numbers with Grok 4.6 in the calculator, and keep routing discipline: the model price is a line item, but the agent loop is where cost blowups live. Google's Gemini 3.8 Flash (Sept 2, 2026) — $0.75/$3.75 per 1M through Dec 31 — now undercuts even Grok 4.6's input price and claims the top of the DeepSWE v1.1 leaderboard (Google-reported, unverified at launch), so the "cheapest frontier coding model 2026" race now has a third contender alongside Grok 4.6 and Sol. If you're quoting fixed-bid agent work, this is the week to recheck which model the quote assumes — and the agency cost guide is the place to re-ground pricing context. Model choice is a margin lever every agency should revisit with a cheaper model class now on the table. For the subscription story on SpaceXAI's other agent products, see Grok Bot's always-on agent team, and for model-routing discipline on small tasks, Muse Spark.
Frequently asked questions
What is Grok 4.6?
Grok 4.6 is SpaceXAI's (formerly xAI) latest frontier model, released August 12, 2026 and positioned by the company for long-running agents and ambitious interactive and visual work. API pricing is $2 per 1M input tokens and $6 per 1M output tokens, with a fast variant at 2x the price.
How does Grok 4.6 pricing compare to GPT-5.6 Sol?
Against GPT-5.6 Sol at $4/$20 per 1M tokens (promotional through at least Nov 21, 2026), Grok 4.6 is 50%+ cheaper on input. On output tokens — the dimension that dominates cost in reasoning-heavy agent workloads — $6 vs $20 works out to 70% cheaper.
Does Grok 4.6 have a 500K-token context window?
Artificial Analysis lists a 500,000-token context window for Grok 4.6 and scores the model 61 on its Intelligence Index, matching GPT-5.6 Sol (max). SpaceXAI's own announcement does not state a context size, so the 500K figure is attributed to Artificial Analysis.
An agency that routes models for cost — not one that bills by habit
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Sources
- SpaceXAI (x.ai), "Grok 4.6" announcement (Aug 12, 2026): x.ai/news/grok-4-6
- Artificial Analysis — Grok 4.6 model page: artificialanalysis.ai/models/grok-4-6
- Artificial Analysis, "Grok 4.6 benchmarks & analysis" (Aug 12, 2026): artificialanalysis.ai/articles/grok-4-6-benchmarks-and-analysis
- Artificial Analysis — GPT-5.6 Sol model page ($4/$20 promo comparison, through Nov 21, 2026): artificialanalysis.ai/models/gpt-5-6-sol
Accuracy note: the 500K-token context window and $0.50 cache-hit pricing are attributed to Artificial Analysis — SpaceXAI's announcement does not state either figure. "50%+ cheaper on input / 70% cheaper on output" is derived math against GPT-5.6 Sol's promotional $4/$20 pricing (effective Aug 21, 2026 through at least Nov 21, 2026; OpenAI, AWS Bedrock); if Sol reverts to $5/$30 after the promo window, the advantage widens to 60%+/80% as originally published. Intelligence Index 61 matching GPT-5.6 Sol (max) reflects Artificial Analysis' chart; no other benchmark or ranking claims are made.