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Gemini 3.5 Flash vs Grok 4.20

At a glance
GoogleGemini 3.5 Flash

Google's high-speed thinking model for agentic workflows, chat, and coding.

861.0M ctx$1.50/$9.00 per M#11/92
xAIGrok 4.20

xAI's newest flagship model with industry-leading speed and agentic tool calling.

862M ctx$1.25/$2.50 per M#12/92
AI Output
All AI outputs

No captured outputs for these models yet.

Benchmarks
See rankings
GoogleGemini 3.5 Flash
Reasoning
AgenticInsufficient data
Sources:Epoch ECI·Epoch AI·OpenRouter· as of 2026-07-10
Smarter
Capability
CapabilityECI86.2
Reasoning & Knowledge
Graduate Science92.8%Factual Recall68.4%
Math
Competition Math95.6%Research Math39.0%
Coding
Real-World Coding79.3%
Agentic
Terminal Tasks—Novel Reasoning72.1%
xAIGrok 4.20
Reasoning
CodingInsufficient data
ReasoningInsufficient data
MathInsufficient data
Sources:Epoch ECI·Epoch AI·OpenRouter· as of 2026-07-10
Cheaper
Capability
CapabilityECI85.7
Reasoning & Knowledge
Graduate Science—Factual Recall—
Math
Competition Math—Research Math—
Coding
Real-World Coding—
Agentic
Terminal Tasks57.3%Novel Reasoning65.1%
Specs
GoogleGemini 3.5 Flash
1.0M
Context
66K
Max output
May 2026
Released
xAIGrok 4.20
2M
Context
16K
Max output
Mar 2026
Released
Capabilities
GoogleGemini 3.5 Flash
Vision
Audio
Reasoning
xAIGrok 4.20
Vision
Audio
Reasoning
Pricing
GoogleGemini 3.5 Flash
Live pricing, shown before you run
Input$1.50/M tokens
Output$9.00/M tokens
Reasoning$9.00/M tokens
Cache read$0.15/M tokens
Cache write$0.08/M tokens
Image input$1.50/M tokens
Audio input$3.00/M tokens
Web search$0.01/search
xAIGrok 4.20
Live pricing, shown before you run
Input$1.25/M tokens
Output$2.50/M tokens
Cache read$0.20/M tokens
Web search$0.005/search
Chat with Gemini 3.5 FlashGo to model
Chat with Grok 4.20Go to model
Frequently Asked Questions: Gemini 3.5 Flash vs Grok 4.20▼

Which is better, Gemini 3.5 Flash or Grok 4.20?

▼

Based on the Capability Index, Gemini 3.5 Flash scores higher (86.2 vs 85.7). However, "better" depends on your use case — pricing, speed, context window, and specific capability needs all matter.

Which is cheaper, Gemini 3.5 Flash or Grok 4.20?

▼

Grok 4.20 has a lower blended cost. Gemini 3.5 Flash: $1.50 input / $9.00 output. Grok 4.20: $1.25 input / $2.50 output.

Which has a larger context window, Gemini 3.5 Flash or Grok 4.20?

▼

Grok 4.20 has a larger context window: Gemini 3.5 Flash supports 1M tokens vs Grok 4.20 at 2M tokens.

Do both Gemini 3.5 Flash and Grok 4.20 support vision?

▼

Yes, both Gemini 3.5 Flash and Grok 4.20 support vision/image input.

What are the key differences between Gemini 3.5 Flash and Grok 4.20?

▼

Gemini 3.5 Flash and Grok 4.20 have similar overall capabilities. The main differences lie in pricing, context window size, and provider-specific strengths. Use this comparison page to review all metrics side by side.

Which model should I choose for my use case?

▼

If cost is your priority, choose the cheaper option. If you need the highest intelligence for complex tasks, pick the higher-scoring model. For long documents or codebases, choose the larger context window. You can try both Gemini 3.5 Flash and Grok 4.20 for free on idapt.app to see which performs better for your specific needs.

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