Grok 4.20 (Reasoning) vs Gemini Robotics-ER 1.6 Preview vs Kimi K2.6
Grok 4.20 (Reasoning) comes out ahead, 56 to 51 and 50 on our weighted score, and it is the cheaper option too.
- Our pick
xAIGrok 4.20 (Reasoning)
56/100- ECI152.0
- Price$1.25 / $2.50
- Context1M
GoogleGemini Robotics-ER 1.6 Preview
50/100- ECI—
- Price$1.00 / $5.00
- Context131K
Moonshot AIKimi K2.6
51/100- ECI151.1
- Price$0.95 / $4.00
- Context262K
Grok 4.20 (Reasoning) is our pick
Grok 4.20 (Reasoning) is the better all-round choice, scoring 56/100 against Kimi K2.6 (51) and Gemini Robotics-ER 1.6 Preview (50). It leads on price and context window. Gemini Robotics-ER 1.6 Preview wins on inputs & features. The score weighs price 50%, inputs & features 30%, context window 20%. None of the shared benchmarks cover every model here yet, so capability is left out of this verdict.
- CapabilityNot enough dataNo independent benchmark covers every model here yet
- Lowest priceGrok 4.20 (Reasoning)Grok 4.20 (Reasoning) $1.56 · Kimi K2.6 $1.71 · Gemini Robotics-ER 1.6 Preview $2.00 per 1M tokens (3:1 blend)
- Longest contextGrok 4.20 (Reasoning)Grok 4.20 (Reasoning) 1,000,000 · Kimi K2.6 262,144 · Gemini Robotics-ER 1.6 Preview 131,072 tokens
- Widest inputsGemini Robotics-ER 1.6 PreviewGrok 4.20 (Reasoning): Text, Images, PDFs · Gemini Robotics-ER 1.6 Preview: Text, Images, Audio, Video · Kimi K2.6: Text, Images, Video
- Self-hostingKimi K2.6Publishes downloadable weights
| Measure | Weight | Grok 4.20 (Reasoning) | Gemini Robotics-ER 1.6 Preview | Kimi K2.6 |
|---|---|---|---|---|
| Price | 50% | 41 | 36 | 39 |
| Inputs & features | 30% | 80 | 90 | 80 |
| Context window | 20% | 60 | 24 | 37 |
| Overall | 100% | 56/100 | 50/100 | 51/100 |
Left out because at least one model lacks the data: capability. The remaining weights were rescaled.
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | Grok 4.20 (Reasoning)xAI | Gemini Robotics-ER 1.6 PreviewGoogle | Kimi K2.6Moonshot AI |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | 152.0 (best) | — | 151.1 |
| ECI rank | #41 of 148 (best) | — | #45 of 148 |
| GPQA DiamondGraduate-level science questions | 89.3% | — | 90.8% (best) |
| FrontierMath Tiers 1–3Research-level mathematics | 44.9% | — | 57.2% (best) |
| OTIS Mock AIME 2024–2025Competition mathematics | 92.2% | — | 96.1% (best) |
| SWE-bench VerifiedFixing real GitHub issues | — | — | 76.7% |
| SimpleQA VerifiedShort factual questions | 30.2% | — | 34.9% (best) |
| Price per million tokens | |||
| Input | $1.25 | $1.00 | $0.95 (best) |
| Output | $2.50 (best) | $5.00 | $4.00 |
| Cached input | $0.20 | — | $0.16 (best) |
| Blended (3:1) | $1.56 (best) | $2.00 | $1.71 |
| Long-context rate | Over 200K: $2.50 / $5.00 | Same rate | Same rate |
| Price source | Official xAI API | Median of 1 providers | Official Moonshot AI API |
| Limits | |||
| Context window | 1,000,000 tokens (best) | 131,072 tokens | 262,144 tokens |
| Max output | 30,000 tokens | 65,536 tokens | 262,144 tokens (best) |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | Yes | Yes | Yes |
| PDFs | Yes | No | No |
| Audio | No | Yes | No |
| Video | No | Yes | Yes |
| Reasoning | Yes | Yes | Yes |
| Tool calling | Yes | Yes | Yes |
| Structured output | Yes | Yes | Yes |
| Availability | |||
| Weights | Proprietary | Proprietary | Open |
| API model ID | grok-4.20-0309-reasoning | — | kimi-k2.6 |
| API providers | 11 | 1 | 46 (best) |
| Released | Mar 9, 2026 | Apr 14, 2026 | Apr 21, 2026 |
| Knowledge cutoff | — | Jan 2025 | Jan 2025 |
What would a month cost?
Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.
- Grok 4.20 (Reasoning)$17.50
- Gemini Robotics-ER 1.6 Preview$20.00
- Kimi K2.6$17.50
Which should you choose?
Which is better: Grok 4.20 (Reasoning), Gemini Robotics-ER 1.6 Preview or Kimi K2.6?
Grok 4.20 (Reasoning) is the better all-round choice, scoring 56/100 against Kimi K2.6 (51) and Gemini Robotics-ER 1.6 Preview (50). It leads on price and context window. Gemini Robotics-ER 1.6 Preview wins on inputs & features. The score weighs price 50%, inputs & features 30%, context window 20%. None of the shared benchmarks cover every model here yet, so capability is left out of this verdict.
Which is cheaper, Grok 4.20 (Reasoning), Gemini Robotics-ER 1.6 Preview or Kimi K2.6?
Grok 4.20 (Reasoning) is cheaper at $1.25 input / $2.50 output per million tokens (official xAI API price). Kimi K2.6 costs $0.95 input / $4.00 output per million tokens (official Moonshot AI API price); Gemini Robotics-ER 1.6 Preview costs $1.00 input / $5.00 output per million tokens (median across 1 API provider). At a typical mix of three input tokens to one output token, that is $1.56 per million tokens for Grok 4.20 (Reasoning) versus $1.71 for Kimi K2.6 (1.1× as much) and $2.00 for Gemini Robotics-ER 1.6 Preview (1.3× as much).
Which scores higher on benchmarks?
There is no independent benchmark that covers all three models yet. Grok 4.20 (Reasoning) has an ECI of 152.0, Gemini Robotics-ER 1.6 Preview has not been scored yet and Kimi K2.6 has an ECI of 151.1.
Which is better for coding?
There are no published SWE-bench Verified results for Grok 4.20 (Reasoning) and Gemini Robotics-ER 1.6 Preview yet, so there is no like-for-like coding score. Test both on a sample of your own tasks. All three support tool calling for agent workflows.
Which has the bigger context window?
Grok 4.20 (Reasoning) has the largest context window at 1,000,000 tokens, against 262,144 for Kimi K2.6 and 131,072 for Gemini Robotics-ER 1.6 Preview. Maximum output per response: Grok 4.20 (Reasoning) up to 30,000, Gemini Robotics-ER 1.6 Preview up to 65,536, Kimi K2.6 up to 262,144 tokens.
Which can read images, PDFs, audio or video?
Grok 4.20 (Reasoning) accepts text, images and PDFs; Gemini Robotics-ER 1.6 Preview accepts text, images, audio and video; Kimi K2.6 accepts text, images and video. Gemini Robotics-ER 1.6 Preview handles the widest range of inputs.
Are any of these open source?
Kimi K2.6 publishes its weights and can be self-hosted; Grok 4.20 (Reasoning) and Gemini Robotics-ER 1.6 Preview is proprietary.
Which is newer?
Kimi K2.6 is the newest, released Apr 21, 2026. Gemini Robotics-ER 1.6 Preview came out Apr 14, 2026; Grok 4.20 (Reasoning) came out Mar 9, 2026. Knowledge cutoff: Gemini Robotics-ER 1.6 Preview Jan 2025, Kimi K2.6 Jan 2025.
How do you decide the winner?
Each model gets a 0–100 score on capability (50%, independent benchmark results); price (25%, blended price per million tokens (3 input : 1 output), log scale); inputs & features (15%, image, PDF, audio and video input, tool calling, structured output and reasoning); context window (10%, maximum tokens per request, log scale). Dimensions missing for any model are dropped and the remaining weights rescaled, so every model is judged on the same evidence. Specs and prices come from public model listings and the labs’ own API pages; capability scores come from independent benchmark runs. Data updated Oct 4, 2026.
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