Gemini 3.1 Pro vs Grok 4.5
Pricing verdict: Gemini 3.1 Pro vs Grok 4.5: input pricing is tied at $2.00/M, Grok 4.5 is cheaper for output-heavy usage ($6.00/M output), and Gemini 3.1 Pro is better for long-context tasks (1,000,000 tokens).
Direct answer: input pricing is tied. Choose Grok 4.5 for cheaper output and choose Gemini 3.1 Pro when your workload needs longer context.
Compare API pricing, input and output token costs, context windows, and monthly estimates on one page so you can pick the right model fast.
Cost Comparison (1000 input + 500 output tokens, 100 requests/day)
Gemini 3.1 Pro
Grok 4.5
Cost Differences
Grok 4.5 costs less than Gemini 3.1 Pro
Quick Recommendation
Winner for direct API pricing: Grok 4.5. At the default workload, Grok 4.5 saves about $9.00/month ($109.50/year) versus Gemini 3.1 Pro.
Feature Comparison
| Feature | Gemini 3.1 Pro | Grok 4.5 |
|---|---|---|
| Provider | xAI | |
| Input Price | $2.00/1M tokens | $2.00/1M tokens |
| Output Price | $12.00/1M tokens | $6.00/1M tokens |
| Context Window | 1,000,000 tokens | 500,000 tokens |
| Max Output | 65,536 tokens | 131,072 tokens |
| Category | flagship | flagship |
| Capabilities | textvisionaudiovideocodereasoning | textvisioncodereasoning |
| Release Date | 2/19/2026 | 7/8/2026 |
Gemini 3.1 Pro vs Grok 4.5: Which Should You Choose?
Choosing between Gemini 3.1 Pro and Grok 4.5 depends on your priorities: cost efficiency, context length, or raw capability. Both models charge $2.00/1M input tokens, but Grok 4.5 is cheaper on output at $6.00/1M. Meanwhile, Gemini 3.1 Pro offers a significantly larger context window at 1,000,000 tokens vs 500,000 for Grok 4.5.
These models come from different providers — Google and xAI — which means different API ecosystems, SDKs, rate limits, and terms of service. If you're already integrated with Google, switching to xAIinvolves migration effort beyond just pricing. Factor in your existing infrastructure when deciding.
Both models are in the flagship category, making this a direct head-to-head comparison. At scale — say 10,000 requests per day — the cost difference adds up: Grok 4.5 would save you roughly $900.00/month compared to Gemini 3.1 Pro. For startups and indie developers, that difference can be significant.
Output costs matter too. Gemini 3.1 Pro charges $12.00/1M output tokens vs $6.00 for Grok 4.5. For generation-heavy workloads (content creation, code generation, summarization), output pricing often dominates your bill. Grok 4.5 has the edge here at $6.00/1M output tokens.
Multimodal capabilities: Both models support vision (image understanding), so you can send images alongside text prompts with either option.
Best Use Cases
Choose Gemini 3.1 Pro when:
- • You need a larger context window (1,000,000 tokens)
- • You need more capabilities (audio, video)
- • You're already using Google's API ecosystem
Choose Grok 4.5 when:
- • You need longer outputs (up to 131,072 tokens)
- • You're already using xAI's API ecosystem
Pros and Caveats at a Glance
Gemini 3.1 Pro
- • Input pricing: $2.00/M tokens
- • Output pricing: $12.00/M tokens
- • Context window: 1,000,000 tokens
- • Max output: 65,536 tokens
Watch out for
- • Higher output cost than Grok 4.5
Grok 4.5
- • Input pricing: $2.00/M tokens
- • Output pricing: $6.00/M tokens
- • Context window: 500,000 tokens
- • Max output: 131,072 tokens
Watch out for
- • Smaller context window than Gemini 3.1 Pro
Try Different Scenarios
Use the calculator below to see how costs change with different usage patterns
Gemini 3.1 Pro (Google)
Grok 4.5 (xAI)
Start using Gemini 3.1 Pro today
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Sign Up for xAI →Frequently Asked Questions
Which is cheaper, Gemini 3.1 Pro or Grok 4.5?▼
What is the context window difference between Gemini 3.1 Pro and Grok 4.5?▼
Which model is better for AI Agent / Agentic Workflows?▼
Which model has better overall pricing for heavy usage?▼
Where can I compare Google and xAI API pricing beyond this model matchup?▼
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