By xAILearning Objectives
- Understand what Grok 4.6 changed relative to Grok 4.5 and where the gains actually landed
- Read xAI's published benchmark table critically — where Grok 4.6 leads the frontier and where it clearly trails
- Decide when Grok 4.6's price and agentic strengths make it the right model for a workload
What Is Grok 4.6?
Grok 4.6 is the flagship model from xAI, the unit operating under SpaceX since the February 2026 acquisition, released on August 12, 2026. xAI describes its focus as long-running agents and more ambitious interactive and visual work — the kind of multi-step task where a model researches, analyses a domain, and refines its own output over many turns.
The headline number is 61 on the Artificial Analysis Intelligence Index, up from Grok 4.5's 56. That puts it level with GPT-5.6 Sol Max at 61 and just behind Claude Fable 5 Max at 62 — the first time an xAI model has drawn even with the top of the field on that composite.
💡Key Concept
What "long-running agent" improvements mean here. xAI attributes the gains to more self-testing and verification — the model checking its own work before moving to the next step. That matters most on trajectories with many sequential steps, where a single unverified error compounds through everything after it. It is why Grok 4.6's largest jumps are on multi-step agentic benchmarks rather than on single-shot reasoning.
✅Tip
Access Grok 4.6: available now in Cursor and Grok Build, through the xAI API, and via partners including OpenRouter, Vercel and Cloudflare.
The Benchmark Picture
xAI published a full comparison table at launch. Read in full it does not show a clean sweep — it shows a model that has closed most of the gap to the frontier, leads on professional-domain and long-horizon work, and still trails clearly on terminal-style tasks.
| Benchmark | Grok 4.6 | Grok 4.5 | GPT-5.6 Sol Max | Fable 5 Max |
|---|---|---|---|---|
| Artificial Analysis Intelligence Index | 61 | 56 | 61 | 62 |
| GDPVal-AA v2 | 1753 | 1526 | 1728 | 1741 |
| CursorBench v3.2 | 69.9% | 66.7% | 67.2% | 70.5% |
| DeepSWE v1.1 | 65.9% | 54% | 73% | 70% |
| FrontierCode v1.1 | 61.3% | 56.6% | 60.6% | 63.6% |
| APEX-Agents | 57.5% | 47.1% | 56.7% | 59.2% |
| Terminal-Bench v3.0 | 26% | 15.7% | 34.6% | 34.1% |
| APEX-SWE | 56.4% | 53.6% | — | 58.8% |
| AA-Briefcase | 1577 | 1313 | 1502 | 1574 |
| Harvey LAB | 15.8% | 12.9% | 2.5% | 11.3% |
Three readings are worth separating:
Against Grok 4.5, the jump is real and broad. Every benchmark improved, and several moved a long way — DeepSWE from 54% to 65.9%, Terminal-Bench from 15.7% to 26%, APEX-Agents from 47.1% to 57.5%, and AA-Briefcase from 1313 to 1577. This is a generational step, not a point release.
Against GPT-5.6 Sol Max, Grok 4.6 wins more often than it loses — ahead on GDPVal, CursorBench, FrontierCode, APEX-Agents, AA-Briefcase and Harvey LAB, behind on DeepSWE and Terminal-Bench.
Against Claude Fable 5 Max, it mostly trails — behind on the composite index and on every coding benchmark except AA-Briefcase and Harvey LAB, where it leads.
⚠️Warning
Terminal-Bench is the one clear weakness, and it is not close. Grok 4.6 scores 26% against roughly 34% for both GPT-5.6 Sol Max and Fable 5 Max — a gap that survived a large improvement over Grok 4.5's 15.7%. If your workload is terminal-driven agentic work, this is the benchmark that should decide the choice, and it does not favour Grok.
📝Note
Vendor-reported numbers. The entire table comes from xAI's own launch materials, including the competitor scores. Self-reported comparisons tend to be measured under settings favourable to the publisher, and independent replication usually lags a launch by a few weeks. Treat the ordering as more reliable than the exact decimals, and note that xAI published the benchmarks it loses on — which is a point in the table's favour.
Where It Genuinely Leads
The two benchmarks where Grok 4.6 beats both frontier rivals are the most interesting part of the launch, because they are not coding tests:
- Harvey LAB — a legal-domain evaluation, where Grok 4.6 scores 15.8% against Fable 5 Max's 11.3% and GPT-5.6 Sol Max's 2.5%. The spread here is far wider than anywhere else in the table.
- AA-Briefcase — 1577 against 1574 and 1502, a narrow lead over Fable 5 Max and a clear one over GPT-5.6 Sol Max.
- GDPVal-AA v2 — 1753 against 1741 and 1728, again a narrow lead over both.
Read together, these point at professional knowledge work with long documents and many steps, rather than at raw software engineering, as the place Grok 4.6 is strongest relative to the field.
Pricing
- $6 per million output tokens
- Available via the xAI API
- Also on OpenRouter, Vercel and Cloudflare
- Lower latency for interactive use
- Same model quality
- Useful for user-facing loops
- No separate xAI billing needed
- Default model in Grok Build
Pricing is unchanged from Grok 4.5 at $2 and $6 per million tokens, which is the practical argument for moving: the capability step is free. Against the frontier this remains aggressive — the same rate that made Grok 4.5 attractive for high-volume agentic loops, now attached to a materially stronger model.
Grok 4.6 vs. Other Frontier Models
| Model | Headline Strength | Where It Wins | Where It Loses |
|---|---|---|---|
| Grok 4.6 (xAI) | Long-horizon agents at low cost | Legal and professional-domain work; price | Terminal-style agentic tasks |
| Claude Fable 5 Max (Anthropic) | Highest composite score | Most coding benchmarks; DeepSWE | Legal-domain evaluation |
| GPT-5.6 Sol Max (OpenAI) | Broadest agentic ecosystem | DeepSWE and Terminal-Bench | Professional-domain benchmarks |
| Grok 4.5 (xAI) | The prior xAI flagship | Nothing — superseded at the same price | Every benchmark in the table |
Related Tools
- Grok 4.5 — the prior xAI flagship, superseded by this model at identical pricing
- Grok — the consumer Grok chat interface, now powered by Grok 4.6
- Grok Build — xAI's terminal coding agent, where Grok 4.6 is the default model
- Cursor — the coding editor where Grok 4.6 shipped on day one
Strengths
- A genuine generational step — every published benchmark improved over Grok 4.5, several by more than ten points
- Leads the frontier on professional-domain work — beats both GPT-5.6 Sol Max and Fable 5 Max on Harvey LAB, AA-Briefcase and GDPVal
- Unchanged pricing — $2 input and $6 output per million tokens, the same as Grok 4.5, so the capability gain costs nothing
- Long-horizon reliability — added self-verification between steps, which is where multi-step agent runs usually fail
- Wide day-one availability — Cursor, Grok Build, the xAI API, OpenRouter, Vercel and Cloudflare at launch
Limitations and Considerations
- Terminal-Bench is a real gap — 26% against roughly 34% for both frontier rivals, the weakest showing in the table
- Behind Fable 5 Max on most coding benchmarks — including DeepSWE, where it trails by more than four points, and the composite index
- Vendor-reported benchmarks — every figure including the competitor scores comes from xAI, without independent replication at launch
- Closed model — API-only, with no downloadable weights and no self-hosting option
- Context window not published — xAI did not state a context length in the launch materials, so verify it against the API documentation before planning long-document workloads
- Younger enterprise stack — xAI's tooling, support and third-party ecosystem remain less mature than OpenAI's, Anthropic's or Google's
Best Use Cases
| Task | Why Grok 4.6 |
|---|---|
| Long-running research and analysis agents | The self-verification work targets exactly the multi-step trajectories where errors compound |
| Legal and professional-domain workflows | Its widest lead in the whole table is on Harvey LAB, a legal evaluation |
| High-volume agentic loops | $2 and $6 per million tokens is well under the frontier for a model now scoring level with GPT-5.6 Sol Max |
| Coding inside Cursor | Shipped there on day one, and CursorBench is one of its stronger results |
When to choose alternatives:
- Terminal-driven agentic work → GPT-5.6 Sol Max or Claude Fable 5 Max, both around 34% on Terminal-Bench against Grok 4.6's 26%
- Hardest software-engineering tasks → Claude Fable 5 Max, which leads on DeepSWE, FrontierCode and APEX-SWE
- Self-hosting or open weights → an open-weight model such as DeepSeek V4-Pro under MIT
Getting Started
- If you already use Cursor or Grok Build, Grok 4.6 is available there now — in Grok Build it is the default
- For API access, point an existing client at the xAI endpoint and set the model ID to Grok 4.6
- Choose the fast variant only for user-facing interactive loops; it costs twice as much for the same model quality
- Run your own evaluation before trusting the launch table, especially on terminal-style tasks where the published gap is widest
- Confirm the context window against xAI's API documentation before committing to long-document workloads
Key Takeaways
- Grok 4.6 shipped on August 12, 2026 as xAI's flagship, scoring 61 on the Artificial Analysis Intelligence Index — level with GPT-5.6 Sol Max, just behind Claude Fable 5 Max at 62
- It improves on Grok 4.5 across every published benchmark, with the largest jumps in agentic coding and long-horizon work
- Its widest lead over both frontier rivals is on Harvey LAB, a legal-domain evaluation, at 15.8% against 11.3% and 2.5%
- Terminal-Bench is its clearest weakness at 26% against roughly 34% for both rivals, and should decide the choice for terminal-driven agents
- Pricing is unchanged from Grok 4.5 at $2 input and $6 output per million tokens, so the capability step costs nothing to adopt
- Every figure in the comparison table is xAI's own, including the competitor scores — credible, and worth treating as claims until independently reproduced
