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Comparison · 3 models · Updated Oct 4, 2026

Kimi K2.6 vs Gemini Robotics-ER 1.6 Preview vs Grok 4.20 (Reasoning)

Grok 4.20 (Reasoning) comes out ahead, 56 to 51 and 50 on our weighted score, and it is the cheaper option too.

  1. Moonshot AI

    Kimi K2.6

    Released Apr 21, 2026

    51/100
    • ECI151.1
    • Price$0.95 / $4.00
    • Context262K
    Full specs Remove Kimi K2.6

  2. Google

    Gemini Robotics-ER 1.6 Preview

    Released Apr 14, 2026

    50/100
    • ECI—
    • Price$1.00 / $5.00
    • Context131K
    Full specs Remove Gemini Robotics-ER 1.6 Preview
  3. Our pick

    xAI

    Grok 4.20 (Reasoning)

    Released Mar 9, 2026

    56/100
    • ECI152.0
    • Price$1.25 / $2.50
    • Context1M
    Full specs Remove Grok 4.20 (Reasoning)
01 — Verdict

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 PreviewKimi K2.6: Text, Images, Video · Gemini Robotics-ER 1.6 Preview: Text, Images, Audio, Video · Grok 4.20 (Reasoning): Text, Images, PDFs
  • Self-hostingKimi K2.6Publishes downloadable weights
How the score is built
MeasureWeightKimi K2.6Gemini Robotics-ER 1.6 PreviewGrok 4.20 (Reasoning)
Price50%393641
Inputs & features30%809080
Context window20%372460
Overall100%51/10050/10056/100

Left out because at least one model lacks the data: capability. The remaining weights were rescaled.

02 — Side by side

Every spec in one table

Highlighted cells lead their row. Dashes mean the data is not published.

Kimi K2.6 vs Gemini Robotics-ER 1.6 Preview vs Grok 4.20 (Reasoning) specifications side by side
SpecificationKimi K2.6Moonshot AIGemini Robotics-ER 1.6 PreviewGoogleGrok 4.20 (Reasoning)xAI
Capability
Capabilities Index (ECI)151.1—152.0 (best)
ECI rank#45 of 148—#41 of 148 (best)
GPQA DiamondGraduate-level science questions90.8% (best)—89.3%
FrontierMath Tiers 1–3Research-level mathematics57.2% (best)—44.9%
OTIS Mock AIME 2024–2025Competition mathematics96.1% (best)—92.2%
SWE-bench VerifiedFixing real GitHub issues76.7%——
SimpleQA VerifiedShort factual questions34.9% (best)—30.2%
Price per million tokens
Input$0.95 (best)$1.00$1.25
Output$4.00$5.00$2.50 (best)
Cached input$0.16 (best)—$0.20
Blended (3:1)$1.71$2.00$1.56 (best)
Long-context rateSame rateSame rateOver 200K: $2.50 / $5.00
Price sourceOfficial Moonshot AI APIMedian of 1 providersOfficial xAI API
Limits
Context window262,144 tokens131,072 tokens1,000,000 tokens (best)
Max output262,144 tokens (best)65,536 tokens30,000 tokens
Inputs and features
TextYesYesYes
ImagesYesYesYes
PDFsNoNoYes
AudioNoYesNo
VideoYesYesNo
ReasoningYesYesYes
Tool callingYesYesYes
Structured outputYesYesYes
Availability
WeightsOpenProprietaryProprietary
API model IDkimi-k2.6—grok-4.20-0309-reasoning
API providers46 (best)111
ReleasedApr 21, 2026Apr 14, 2026Mar 9, 2026
Knowledge cutoffJan 2025Jan 2025—
03 — Cost

What would a month cost?

Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.

  • Kimi K2.6$17.50
  • Gemini Robotics-ER 1.6 Preview$20.00
  • Grok 4.20 (Reasoning)$17.50
04 — Questions

Which should you choose?

Which is better: Kimi K2.6, Gemini Robotics-ER 1.6 Preview or Grok 4.20 (Reasoning)?

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, Kimi K2.6, Gemini Robotics-ER 1.6 Preview or Grok 4.20 (Reasoning)?

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. Kimi K2.6 has an ECI of 151.1, Gemini Robotics-ER 1.6 Preview has not been scored yet and Grok 4.20 (Reasoning) has an ECI of 152.0.

Which is better for coding?

There are no published SWE-bench Verified results for Gemini Robotics-ER 1.6 Preview and Grok 4.20 (Reasoning) 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: Kimi K2.6 up to 262,144, Gemini Robotics-ER 1.6 Preview up to 65,536, Grok 4.20 (Reasoning) up to 30,000 tokens.

Which can read images, PDFs, audio or video?

Kimi K2.6 accepts text, images and video; Gemini Robotics-ER 1.6 Preview accepts text, images, audio and video; Grok 4.20 (Reasoning) accepts text, images and PDFs. 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; Gemini Robotics-ER 1.6 Preview and Grok 4.20 (Reasoning) 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: Kimi K2.6 Jan 2025, Gemini Robotics-ER 1.6 Preview 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.

05 — Keep comparing

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