Gemini 3.5 Flash vs o3 Pro
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 o3 Pro.
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...
o3 Pro
The o-series of models are trained with reinforcement learning to think before they answer and perform complex reasoning. The o3-pro model uses more compute to think harder and provide consistently...
Technical Specifications
| Specification | Gemini 3.5 Flash | o3 Pro |
|---|---|---|
| Provider | OpenAI | |
| Context Window | 1,048,576 tokens | 200,000 tokens |
| Agent Suitability | 88/100 | N/A |
| Time to First Token (TTFT) | 200 ms | N/A |
| Deployment Model | managed api | managed api |
| Production Stability | stable | stable |
| API Available | Yes | Yes |
| Released Date | 2026-05-19 | 2025-06-10 |
API Pricing Comparison
Input Price per Million Tokens
Gemini 3.5 Flash
$1.50
o3 Pro
$20.00
Output Price per Million Tokens
Gemini 3.5 Flash
$9.00
o3 Pro
$80.00
Want to test both models live?
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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
o3 Pro Quirks & Gotchas
No developer gotchas reported.