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Comparison · 2 models · Updated Oct 4, 2026

Grok 4.20 (Reasoning) vs Gemini 3.6 Flash

Gemini 3.6 Flash comes out ahead, 73 to 68 on our weighted score, and it is the cheaper option too.

  1. xAI

    Grok 4.20 (Reasoning)

    Released Mar 9, 2026

    68/100
    • ECI152.0
    • Price$1.25 / $2.50
    • Context1M
    Full specs Remove Grok 4.20 (Reasoning)
  2. Our pick

    Google

    Gemini 3.6 Flash

    Released Jul 21, 2026

    73/100
    • ECI154.3
    • Price$0.75 / $3.75
    • Context1.05M
    Full specs Remove Gemini 3.6 Flash

  3. Add a model

    Make it a three-way comparison.

01 — Verdict

Gemini 3.6 Flash is our pick

Gemini 3.6 Flash is the better all-round choice, scoring 73/100 against Grok 4.20 (Reasoning) (68). It leads on capability and inputs & features. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

  • CapabilityGemini 3.6 FlashCapabilities Index (ECI): Gemini 3.6 Flash 154.3 · Grok 4.20 (Reasoning) 152.0
  • Lowest priceGemini 3.6 FlashGemini 3.6 Flash $1.50 · Grok 4.20 (Reasoning) $1.56 per 1M tokens (3:1 blend)
  • Longest contextGemini 3.6 FlashGemini 3.6 Flash 1,048,576 · Grok 4.20 (Reasoning) 1,000,000 tokens
  • Widest inputsGemini 3.6 FlashGrok 4.20 (Reasoning): Text, Images, PDFs · Gemini 3.6 Flash: Text, Images, PDFs, Audio, Video
  • Self-hostingNo open weightsBoth are available only through APIs
How the score is built
MeasureWeightGrok 4.20 (Reasoning)Gemini 3.6 Flash
CapabilityCapabilities Index (ECI)50%8184
Price25%4142
Inputs & features15%80100
Context window10%6061
Overall100%68/10073/100
02 — Side by side

Every spec in one table

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

Grok 4.20 (Reasoning) vs Gemini 3.6 Flash specifications side by side
SpecificationGrok 4.20 (Reasoning)xAIGemini 3.6 FlashGoogle
Capability
Capabilities Index (ECI)152.0154.3 (best)
ECI rank#41 of 148#34 of 148 (best)
GPQA DiamondGraduate-level science questions89.3%94.1% (best)
FrontierMath Tiers 1–3Research-level mathematics44.9%59.0% (best)
OTIS Mock AIME 2024–2025Competition mathematics92.2%94.2% (best)
SimpleQA VerifiedShort factual questions30.2%66.2% (best)
Price per million tokens
Input$1.25$0.75 (best)
Output$2.50 (best)$3.75
Cached input$0.20$0.075 (best)
Blended (3:1)$1.56$1.50 (best)
Long-context rateOver 200K: $2.50 / $5.00Same rate
Price sourceOfficial xAI APIOfficial Google API
Limits
Context window1,000,000 tokens1,048,576 tokens (best)
Max output30,000 tokens65,536 tokens (best)
Inputs and features
TextYesYes
ImagesYesYes
PDFsYesYes
AudioNoYes
VideoNoYes
ReasoningYesYesminimal · low · medium · high
Tool callingYesYes
Structured outputYesYes
Availability
WeightsProprietaryProprietary
API model IDgrok-4.20-0309-reasoninggemini-3.6-flash
API providers1125 (best)
ReleasedMar 9, 2026Jul 21, 2026
Knowledge cutoff—Mar 2026
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.

  • Grok 4.20 (Reasoning)$17.50
  • Gemini 3.6 Flash$15.00
04 — Questions

Which should you choose?

Which is better: Grok 4.20 (Reasoning) or Gemini 3.6 Flash?

Gemini 3.6 Flash is the better all-round choice, scoring 73/100 against Grok 4.20 (Reasoning) (68). It leads on capability and inputs & features. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

Which is cheaper, Grok 4.20 (Reasoning) or Gemini 3.6 Flash?

Gemini 3.6 Flash is cheaper at $0.75 input / $3.75 output per million tokens (official Google API price). Grok 4.20 (Reasoning) costs $1.25 input / $2.50 output per million tokens (official xAI API price). At a typical mix of three input tokens to one output token, that is $1.50 per million tokens for Gemini 3.6 Flash versus $1.56 for Grok 4.20 (Reasoning) (1× as much).

Which scores higher on benchmarks?

Gemini 3.6 Flash scores higher on the Capabilities Index (ECI): Gemini 3.6 Flash 154.3 (#34 of 148) and Grok 4.20 (Reasoning) 152.0 (#41 of 148). The confidence ranges of the top two overlap (152.6–156.3 vs 149.3–154.4), so treat the gap as small. On individual benchmarks: GPQA Diamond — Gemini 3.6 Flash 94.1%, Grok 4.20 (Reasoning) 89.3%; FrontierMath Tiers 1–3 — Gemini 3.6 Flash 59.0%, Grok 4.20 (Reasoning) 44.9%; OTIS Mock AIME 2024–2025 — Gemini 3.6 Flash 94.2%, Grok 4.20 (Reasoning) 92.2%; SimpleQA Verified — Gemini 3.6 Flash 66.2%, Grok 4.20 (Reasoning) 30.2%.

Which is better for coding?

There are no published SWE-bench Verified results for Grok 4.20 (Reasoning) and Gemini 3.6 Flash yet, so there is no like-for-like coding score. On overall capability, Gemini 3.6 Flash leads, which tends to carry over to coding, but test on your own codebase. Both support tool calling for agent workflows.

Which has the bigger context window?

Gemini 3.6 Flash has the largest context window at 1,048,576 tokens, against 1,000,000 for Grok 4.20 (Reasoning). Maximum output per response: Grok 4.20 (Reasoning) up to 30,000, Gemini 3.6 Flash up to 65,536 tokens.

Which can read images, PDFs, audio or video?

Grok 4.20 (Reasoning) accepts text, images and PDFs; Gemini 3.6 Flash accepts text, images, PDFs, audio and video. Gemini 3.6 Flash handles the widest range of inputs.

Are any of these open source?

No. Grok 4.20 (Reasoning) and Gemini 3.6 Flash are proprietary and only available through APIs and apps.

Which is newer?

Gemini 3.6 Flash is the newest, released Jul 21, 2026. Grok 4.20 (Reasoning) came out Mar 9, 2026. Knowledge cutoff: Gemini 3.6 Flash Mar 2026.

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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