GPT-5.5 vs Grok 4.1 Fast
GPT-5.5 vs Grok 4.1 Fast: Grok 4.1 Fast is cheaper for input-heavy usage ($0.20/M vs $5.00/M input tokens), while Grok 4.1 Fast is better for long-context tasks (2,000,000 tokens).
Direct answer: choose Grok 4.1 Fast for lower token spend and choose Grok 4.1 Fast when your workload needs longer context.
Common pricing searches covered on this page: GPT-5.5 vs Grok 4.1 Fast • GPT-5.5 vs Grok 4.1 Fast pricing • GPT-5.5 vs Grok 4.1 Fast API pricing and 5 5 vs grok 4 1 fast pricing.
Cost Comparison (1000 input + 500 output tokens, 100 requests/day)
GPT-5.5
Grok 4.1 Fast
Cost Differences
Grok 4.1 Fast costs less than GPT-5.5
Quick Recommendation
Winner for direct API pricing: Grok 4.1 Fast. At the default workload, Grok 4.1 Fast saves about $58.65/month ($713.575/year) versus GPT-5.5.
Feature Comparison
| Feature | GPT-5.5 | Grok 4.1 Fast |
|---|---|---|
| Provider | OpenAI | xAI |
| Input Price | $5.00/1M tokens | $0.20/1M tokens |
| Output Price | $30.00/1M tokens | $0.50/1M tokens |
| Context Window | 1,050,000 tokens | 2,000,000 tokens |
| Max Output | 128,000 tokens | 131,072 tokens |
| Category | flagship | efficient |
| Capabilities | textvisioncodereasoning | textreasoningcode |
| Release Date | 4/24/2026 | 1/15/2026 |
GPT-5.5 vs Grok 4.1 Fast: Which Should You Choose?
Choosing between GPT-5.5 and Grok 4.1 Fast depends on your priorities: cost efficiency, context length, or raw capability. Grok 4.1 Fast is the more affordable option at $0.20/1M input tokens — 96% cheaper than GPT-5.5. Meanwhile, Grok 4.1 Fast offers a significantly larger context window at 2,000,000 tokens vs 1,050,000 for GPT-5.5.
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-5.5 is a flagship model while Grok 4.1 Fast is efficient. This means they're optimized for different workloads. GPT-5.5 is built for complex tasks that require deeper reasoning, while Grok 4.1 Fast offers better value for routine operations.
Output costs matter too. GPT-5.5 charges $30.00/1M output tokens vs $0.50 for Grok 4.1 Fast. For generation-heavy workloads (content creation, code generation, summarization), output pricing often dominates your bill. Grok 4.1 Fast has the edge here at $0.50/1M output tokens.
Multimodal capabilities: GPT-5.5 supports vision (image inputs) while Grok 4.1 Fast is text-only. If your application needs image understanding, this narrows your choice.
Best Use Cases
Choose GPT-5.5 when:
- • You need more capabilities (vision)
- • You're already using OpenAI's API ecosystem
Choose Grok 4.1 Fast when:
- • Budget is a primary concern
- • You need a larger context window (2,000,000 tokens)
- • You need longer outputs (up to 131,072 tokens)
- • You're already using xAI's API ecosystem
- • You're running high-volume, latency-sensitive workloads
Pros and Caveats at a Glance
GPT-5.5
- • Input pricing: $5.00/M tokens
- • Output pricing: $30.00/M tokens
- • Context window: 1,050,000 tokens
- • Max output: 128,000 tokens
Watch out for
- • Higher input cost than Grok 4.1 Fast
- • Higher output cost than Grok 4.1 Fast
- • Smaller context window than Grok 4.1 Fast
Grok 4.1 Fast
- • Input pricing: $0.20/M tokens
- • Output pricing: $0.50/M tokens
- • Context window: 2,000,000 tokens
- • Max output: 131,072 tokens
Watch out for
- • Trade-offs are minor in this matchup.
Try Different Scenarios
Use the calculator below to see how costs change with different usage patterns
GPT-5.5 (OpenAI)
Grok 4.1 Fast (xAI)
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Which is cheaper, GPT-5.5 or Grok 4.1 Fast?▼
What is the context window difference between GPT-5.5 and Grok 4.1 Fast?▼
Which model is better for AI Agent / Agentic Workflows?▼
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Where can I compare OpenAI and xAI API pricing beyond this model matchup?▼
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