Cost Comparison (1000 input + 500 output tokens, 100 requests/day)
GPT-5.1
Grok 4
Cost Differences
Grok 4 costs more than GPT-5.1
Feature Comparison
| Feature | GPT-5.1 | Grok 4 |
|---|---|---|
| Provider | OpenAI | xAI |
| Input Price | $1.25/1M tokens | $3.00/1M tokens |
| Output Price | $10.00/1M tokens | $15.00/1M tokens |
| Context Window | 1,000,000 tokens | 256,000 tokens |
| Max Output | 131,072 tokens | 131,072 tokens |
| Category | flagship | reasoning |
| Capabilities | textvisionaudiocodereasoning | textvisionreasoningcode |
| Release Date | 11/12/2025 | 7/9/2025 |
GPT-5.1 vs Grok 4: Which Should You Choose?
Choosing between GPT-5.1 and Grok 4 depends on your priorities: cost efficiency, context length, or raw capability. GPT-5.1 is the more affordable option at $1.25/1M input tokens — 58% cheaper than Grok 4. Meanwhile, GPT-5.1 offers a significantly larger context window at 1,000,000 tokens vs 256,000 for Grok 4.
These models come from different providers — OpenAI and xAI — which means different API ecosystems, SDKs, rate limits, and terms of service. If you're already integrated with OpenAI, switching to xAIinvolves migration effort beyond just pricing. Factor in your existing infrastructure when deciding.
These models target different tiers: GPT-5.1 is a flagship model while Grok 4 is reasoning. This means they're optimized for different workloads. GPT-5.1 is built for complex tasks that require deeper reasoning, while Grok 4 offers better value for routine operations.
Output costs matter too. GPT-5.1 charges $10.00/1M output tokens vs $15.00 for Grok 4. For generation-heavy workloads (content creation, code generation, summarization), output pricing often dominates your bill. GPT-5.1 has the edge here at $10.00/1M 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 GPT-5.1 when:
- • Budget is a primary concern
- • You need a larger context window (1,000,000 tokens)
- • You need more capabilities (audio)
- • You're already using OpenAI's API ecosystem
Choose Grok 4 when:
- • You're already using xAI's API ecosystem
Try Different Scenarios
Use the calculator below to see how costs change with different usage patterns
GPT-5.1 (OpenAI)
Grok 4 (xAI)
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