Gemini 3.1 Flash vs Gemini 3.1 Pro Preview Custom Tools
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 3.1 Flash and Gemini 3.1 Pro Preview Custom Tools.
Gemini 3.1 Flash
Gemini 3.1 Flash is Google's high-speed, cost-efficient multimodal model in the 3.1 generation, purpose-built for high-volume content synthesis, classification, and intelligent routing at scale. Featuring a 1-million-token context window, it can process large batches of documents, customer data, or multimedia content in a single inference pass, dramatically reducing pipeline complexity. At just $0.25/MTok for input, it is one of the most affordable routes to Google-caliber multimodal AI, making it an ideal backbone for production pipelines, data enrichment workflows, and high-frequency API integrations.
Gemini 3.1 Pro Preview Custom Tools
Gemini 3.1 Pro Preview Custom Tools is a variant of Gemini 3.1 Pro that improves tool selection behavior by preventing overuse of a general bash tool when more efficient third-party...
Technical Specifications
| Specification | Gemini 3.1 Flash | Gemini 3.1 Pro Preview Custom Tools |
|---|---|---|
| Provider | ||
| Context Window | 1,000,000 tokens | 1,048,756 tokens |
| Agent Suitability | 86/100 | N/A |
| Time to First Token (TTFT) | 150 ms | N/A |
| Deployment Model | managed api | managed api |
| Production Stability | stable | beta |
| API Available | Yes | Yes |
| Released Date | 2026-04-20 | 2026-02-25 |
API Pricing Comparison
Input Price per Million Tokens
Gemini 3.1 Flash
$0.25
Gemini 3.1 Pro Preview Custom Tools
$2.00
Output Price per Million Tokens
Gemini 3.1 Flash
$1.50
Gemini 3.1 Pro Preview Custom Tools
$12.00
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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 3.1 Flash Quirks & Gotchas
- ▸Most cost-effective Google model — ideal for high-volume pipelines
- ▸Context caching available via Vertex AI for repeated document processing
Gemini 3.1 Pro Preview Custom Tools Quirks & Gotchas
No developer gotchas reported.