Gemini 3.5 Flash vs Grok 4.20
How do these models stack up? Below is an expert side-by-side comparison of specifications, context window capacity, live pricing per million tokens, and standardized benchmark scores for Gemini 3.5 Flash and Grok 4.20.
Gemini 3.5 Flash
Gemini 3.5 Flash is Google's high-efficiency multimodal model, bringing near-Pro level coding and reasoning at Flash-tier cost and speed. It is highly optimized for coding proficiency and parallel agentic execution...
Grok 4.20
Grok 4.20 is xAI's most advanced reasoning model, combining powerful analytical capabilities with unique real-time integration to the X (formerly Twitter) platform data stream. This live data access allows Grok 4.20 to answer queries with up-to-the-minute context, making it invaluable for financial analysis, current events research, and real-time market monitoring. Exceptionally strong in physics, advanced mathematics, and code synthesis, it operates with a 2-million-token context window and is priced at $1.25/MTok for input — delivering frontier-tier reasoning at a highly competitive cost for developers building intelligent agents and analytical tools.
Technical Specifications
| Specification | Gemini 3.5 Flash | Grok 4.20 |
|---|---|---|
| Provider | xAI | |
| Context Window | 1,048,576 tokens | 2,000,000 tokens |
| Agent Suitability | 88/100 | 90/100 |
| Time to First Token (TTFT) | 200 ms | 350 ms |
| Deployment Model | managed api | managed api |
| Production Stability | stable | stable |
| API Available | Yes | Yes |
| Released Date | 2026-05-19 | 2026-05-05 |
API Pricing Comparison
Input Price per Million Tokens
Gemini 3.5 Flash
$1.50
Grok 4.20
$1.25
Output Price per Million Tokens
Gemini 3.5 Flash
$9.00
Grok 4.20
$2.50
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Benchmark Performance Metrics
Scores show the raw performance percentages verified across key evaluation suites. Higher bars indicate superior accuracy and capability in that domain.
Gemini 3.5 Flash Quirks & Gotchas
- ▸Excellent multimodal performance — native video understanding
- ▸Tool calling via Google's native function_declarations in Vertex AI
Grok 4.20 Quirks & Gotchas
- ▸Real-time X data access — unparalleled for current events / financial analysis
- ▸Tool calling API is still maturing — test thoroughly for production agentic use