Grok 4.6 vs GPT-5.6 Sol: Benchmarks, Pricing, Speed & Context Compared

Grok 4.6 (SpaceXAI, August 12, 2026) and GPT-5.6 Sol (OpenAI, July 2026) are the two most interesting frontier releases of the summer — and they tie at 61 on the Artificial Analysis Intelligence Index. But a shared headline number hides two very different models: Grok is the aggressive value play at $2/$6, while Sol is OpenAI's coding and terminal specialist at $5/$30.

This guide compares the two across benchmarks, pricing, speed, latency, and context. Figures are drawn from xAI's launch table, OpenAI's documentation, Artificial Analysis, and independent reviews.

At a Glance

Benchmark Comparison

Here is the head-to-head from xAI's official Grok 4.6 launch table. The overall index is a dead heat, but the row-by-row split tells the real story.

Source: xAI "Introducing Grok 4.6" (Aug 12, 2026). Vendor-reported; third-party scores are the best of self-reported or publicly available results.

Benchmark Head-to-Head

The pattern is clean: Sol dominates the two hardest engineering evaluations — DeepSWE (+7.1 points) and Terminal-Bench (+8.6 points) — while Grok edges ahead on coding-agent rows (CursorBench, FrontierCode, APEX-Agents) by 1–2 points and wins professional knowledge work convincingly. Notably, Grok's Harvey LAB score (15.8%) is 6× Sol's (2.5%), a striking gap in legal-agent work.

Capability Radar

Radar values are normalized (0–100) from the benchmark table for visual comparison only.

Pricing: Grok's Core Advantage

Grok 4.6 is 2.5× cheaper on input and 5× cheaper on output:

Consider a hypothetical agent task using 1M input + 250K output tokens:

At headline rates, that task costs roughly $3.50 on Grok 4.6 vs. $12.50 on GPT-5.6 Sol — a 3.6× difference (and $7 with Grok's twice-priced fast variant). Sol's token efficiency is a real counterweight — OpenAI reports it uses less than half the output tokens of Fable 5 on the Coding Agent Index — but on raw token cost, Grok has room to fail more often before losing its advantage.

Speed & Latency

This is the most nuanced dimension. On standard API serving, Grok is faster to generate; on first token, Sol is faster to start:

And then there's the wildcard: OpenAI is rolling out GPT-5.6 Sol on Cerebras hardware at up to 750 tokens/second — roughly 5× typical frontier throughput and ~9× Grok's 85.8 t/s. That's not yet broadly available, but for latency-critical agents it changes the calculus entirely. On standard serving, Grok generates faster (~86 vs ~60 t/s), but Sol starts answering much sooner (~13.6s vs ~32.3s).

Context Window: Sol Doubles Grok

GPT-5.6 Sol ships a 1,050,000-token context window (128K max output) — more than double Grok 4.6's 500K. For very large repositories, multi-document research, or long agent sessions, Sol holds substantially more working context in a single pass. Both models double their rates above a long-context threshold (Sol at 272K, Grok at 200K), but Sol's ceiling is simply much higher.

Verdict: Which Should You Choose?

The most practical answer is often a router again: Grok 4.6 as the default value lane for routine work, GPT-5.6 Sol escalated for the hardest repository and terminal tasks. Run the same 20–50 tasks through both with an identical harness, and measure completion rate, token efficiency, and human review time — the tie on the headline index means the decision comes down to your specific workload.

Sources

• xAI — Introducing Grok 4.6
• OpenAI — GPT-5.6 launch
• OpenAI — Previewing GPT-5.6 Sol
• OpenAI — GPT-5.6 Sol model page
• Artificial Analysis — OpenAI provider analysis
• Artificial Analysis — GPT-5.6 Sol (high) providers
• Kingy — Grok 4.6 vs GPT-5.6 Sol vs Claude Fable 5
• Coursiv — GPT-5.6 Sol benchmarks & pricing