Grok 4.6 vs Kimi K3: Full Comparison

Grok 4.6 vs Kimi K3: 2T-Parameter Efficiency Play Meets 2.8T Open Weights

Grok 4.6 is xAI's newly launched 1.5-trillion-parameter model — built on the Grok 4.5 foundation with significantly improved supervised fine-tuning and reinforcement learning — explicitly positioned to challenge Kimi K3 while keeping the speed and token efficiency of Grok 4.5. Kimi K3 is Moonshot's shipping ~2.8T model with published pricing and a 1M-token context window. Which one to pick today comes down to whether you want proven, available long-context capacity (Kimi K3) or xAI's post-training-tuned challenger now that it has landed (Grok 4.6). Grok 4.6 launched on August 7, 2026, confirmed by Elon Musk on July 28, 2026 and reported by community trackers on X.

Key Takeaways

• Grok 4.6 launched August 7, 2026; Kimi K3 is also shipping. Both are now available for direct evaluation.
• Parameter counts favor Kimi K3 on raw scale: ~2.8T vs Grok 4.6's confirmed 1.5T. The larger 2T-class step-up is Grok 4.7, arriving weeks later at 2.1T.
• Kimi K3 has a public price: $3 / $15 per 1M input/output tokens with a 1M-token context. Grok 4.6 pricing was not separately published at launch; Grok 4.5's rates are the closest reference.
• Availability today: Kimi K3 is accessible via Moonshot's API and multiple third-party surfaces; Grok 4.6 launched on xAI's own channels (SuperGrok, xAI API, Grok Build) on August 7.
• The Musk claim to watch: Grok 4.6 will challenge Kimi K3 and Claude Opus 4.8 while maintaining speed and token efficiency close to Grok 4.5. Independent benchmarks are still landing.
• Head-to-head data is still thin. Comparisons below reflect vendor statements plus early community signal, not fully independent evaluation.

Grok 4.6 vs Kimi K3 at a Glance

Dimension	Grok 4.6 (xAI)	Kimi K3 (Moonshot)
Parameters	1.5T (confirmed by Elon Musk, July 28, 2026)	~2.8T (per community coverage of Moonshot launch)
Status	Launched August 7, 2026	Shipping
Pricing	Not separately announced at launch; Grok 4.5 baseline ~$2 / $6 per 1M input/output tokens	$3 / $15 per 1M input/output tokens (per third-party pricing writeup)
Context window	Not separately announced (Grok 4.5 baseline applies)	1M tokens (per third-party writeup)
Openness	Closed weights, commercial API	Discussed as open-weights in community coverage
Primary access	xAI channels (SuperGrok, xAI API, Grok Build)	Moonshot API + multiple third-party surfaces
Design goal	Challenge Kimi K3 / Opus 4.8 at Grok 4.5-class speed/efficiency via improved SFT + RL	Frontier scale + long context at competitive price

Every "not separately announced" cell will be updated as xAI publishes model-specific documentation.

Capabilities and Design Philosophy

The two models represent different bets. Kimi K3 leans on raw scale — 2.8 trillion parameters — and a 1M-token context window to compete on frontier tasks and long-document workloads. Community coverage of Moonshot's launch has emphasized front-end coding strength and pricing that undercuts closed-weight rivals.

Grok 4.6, per Musk's July 28 confirmation, is designed around a different axis: keep the Grok 4.5 foundation (1.5T parameters) and push capability through significantly stronger post-training — supervised fine-tuning and reinforcement learning — while preserving Grok 4.5's throughput profile. Grok 4.5 was released July 16, 2026, and community reports credited it with roughly 2x token efficiency versus comparable models and 80 transactions per second, according to third-party writeups. If Grok 4.6's SFT/RL gains hold up, xAI's argument is that Kimi's ~1.3T parameter advantage becomes less decisive on the cost-per-token, latency, and instruction-following axes that dominate real workloads.

That is the pitch. Whether the post-training work actually delivers Kimi-K3-class capability at this scale is exactly what independent benchmarks now need to test. As one active AI observer noted on X, "Kimi service is really good" — a reminder that Kimi K3 has already earned production goodwill, while Grok 4.6 has to earn it from day one.

Benchmarks (or the Absence of Them)

There are no independent head-to-head benchmarks between Grok 4.6 and Kimi K3 as of publication. This section will be filled in as data lands over the coming days.

What exists today:

• Kimi K3: community demos and third-party YouTube evaluations have surfaced positive early impressions on coding and front-end tasks. Moonshot has released the model publicly; independent benchmark reports are still accumulating.
• Grok 4.6: launched August 7, with initial evaluations expected on Arena and community harnesses in the days that follow. Musk's public claim is that it will challenge Kimi K3 and Claude Opus 4.8. That is a vendor forecast; independent measurements are still landing.
• Reference point: Grok 4.5 reportedly scored 29.0% on SWE Marathon per third-party coverage. Grok 4.6 should exceed this if the SFT/RL gains hold, but a confirmed number was not published alongside launch.

Early community impressions are impressions — flag them as such and wait for structured evaluations before making load-bearing decisions.

Pricing and Context

This is the dimension where the comparison is still lopsided, because only one side has separately published numbers.

Kimi K3: $3 per million input tokens, $15 per million output tokens, with a 1M-token context window at flat pricing per third-party pricing coverage. See our Kimi K3 price guide for the full breakdown.

Grok 4.6: xAI did not publish separate API pricing at launch. Since Grok 4.6 shares the 1.5T foundation with Grok 4.5, the closest anchor remains Grok 4.5 at reportedly $2 input / $6 output per million tokens per third-party writeups. If xAI holds that pricing for the 4.6 successor, Grok 4.6 lands materially cheaper than Kimi K3 on output tokens — which is where most agentic and coding workloads spend.

Context window for Grok 4.6 was likewise not separately announced at launch. Grok 4.5's ceiling has not been publicly matched to Kimi K3's 1M-token figure.

Availability and Access

Kimi K3 is available now through Moonshot's API and through downstream platforms. For teams that need a shipping frontier model this quarter, it is one of a small handful of options at this scale. Developers evaluating open-weights alternatives can start with Kimi K3 on kie.ai alongside the direct Moonshot channel.

Grok 4.6 launched on August 7, 2026 through xAI's own surfaces first: the SuperGrok consumer tiers, the xAI API console, and Grok Build. Arena.ai confirmed on July 28 that Grok 4.6 would appear on its evaluation surface the week of launch. Historical rollout patterns suggest EU availability may lag the initial launch, per third-party coverage of Grok 4.5's rollout — teams in that region should confirm regional availability before committing.

For deeper background, see our earlier explainer on what Grok 4.6 actually is and the companion piece on Kimi K3's architecture and positioning.

Which One Should You Use?

Choose Kimi K3 if:

• You need a shipping model with public pricing and a documented 1M-token context window today.
• Your workload benefits from open-weights flexibility (self-hosting, fine-tuning) if that materializes as expected.
• Long-context tasks (repo-scale code, multi-document synthesis) are core to what you're building.

Choose Grok 4.6 if:

• Grok 4.5's speed and token-efficiency profile has already worked for your production workload and you want the post-training-tuned successor on the same foundation.
• You are inside the xAI ecosystem (Grok Build CLI, X integration, SuperGrok) and prefer first-party tooling.
• xAI's Grok 4.5-baseline pricing carries over — plausible from the shared 1.5T foundation, but confirm before large commitments.

Wait and re-evaluate if: you can afford to delay and want to see independent benchmarks before committing. That is likely the right call for most teams — vendor claims are not data, and Grok 4.6's SFT/RL gains still need third-party verification.

Frequently Asked Questions

Is Grok 4.6 better than Kimi K3? Grok 4.6 launched August 7, 2026 as a 1.5T-parameter model built on the Grok 4.5 foundation with significantly improved SFT and RL, per Elon Musk. It targets similar speed and token efficiency to Grok 4.5 while challenging Kimi K3 and Claude Opus 4.8. Independent head-to-head benchmarks are still landing; Kimi K3 remains a shipping model with measurable production performance.

Is Grok 4.6 cheaper than Kimi K3? xAI has not published Grok 4.6-specific API pricing at launch. Kimi K3 lists $3 / $15 per million input/output tokens with a 1M-token context window. Grok 4.5, the direct foundation for 4.6, is $2 input / $6 output per million tokens according to third-party writeups.

What is the parameter count of Grok 4.6 vs Kimi K3? Grok 4.6 is a 1.5-trillion-parameter model built on the same foundation as Grok 4.5, per Elon Musk's July 28, 2026 confirmation. Kimi K3 is roughly 2.8 trillion parameters based on Moonshot's release materials referenced in community coverage. Grok 4.7 (2.1T) is the larger step up expected weeks later.

When was Grok 4.6 released? Grok 4.6 launched on August 7, 2026 through xAI's channels, confirmed by Elon Musk on July 28, 2026 and by Arena.ai the same day. Grok 4.7, a 2.1T model, is expected a few weeks later.

Is Kimi K3 open source and Grok 4.6 not? Kimi K3 has been discussed as an open-weights release in community coverage of Moonshot's launch. Grok 4.6 shipped as a closed-weight commercial release with API access via xAI, consistent with prior Grok versions.

Which model is faster, Grok 4.6 or Kimi K3? Musk's stated design goal for Grok 4.6 is speed and token efficiency close to Grok 4.5 (~80 transactions per second per third-party writeups). Kimi K3's real-world serving speed varies by provider and has been described by observers as a solid production service. No head-to-head throughput comparison has been published yet.

Should I switch from Kimi K3 to Grok 4.6 now that it has launched? Grok 4.6 is now available, so direct evaluation is possible. Kimi K3 remains a known quantity with published pricing and a 1M-context window. Switching decisions should wait for independent evaluations on coding, agentic, and long-context tasks — the training-time SFT/RL gains xAI is claiming still need third-party verification.

What to Watch Next

Three signals will decide this comparison now that Grok 4.6 is live:

1. Grok 4.6 pricing and context-window disclosure. xAI did not separately publish either at launch. If rates match Grok 4.5's reported $2/$6 and the context ceiling extends toward 1M tokens, Kimi K3's structural advantages narrow considerably.
2. Independent benchmarks on coding, agentic tasks, and long-context retrieval — SWE-bench variants, terminal/agent evaluations, and needle-in-haystack tests. The 1.5T-plus-better-post-training thesis lives or dies here.
3. Grok 4.7's arrival. Musk has publicly committed to Grok 4.7 as a 2.1T model "a few weeks later," positioned as better than 4.6 across the board with even better token efficiency. Teams weighing a switch may want to factor that near-term follow-up into their decision.

Building similar chat and reasoning workloads? On kie.ai you can try Grok 4.5, Grok 4.6, and Claude Opus 4.8.