GPT-5.5 Instant vs Grok Code Fast 1
Pricing verdict: GPT-5.5 Instant vs Grok Code Fast 1: Grok Code Fast 1 is cheaper for input-heavy usage ($0.20/M vs $5.00/M input tokens), while GPT-5.5 Instant is better for long-context tasks (1,050,000 tokens).
Direct answer: choose Grok Code Fast 1 for lower token spend and choose GPT-5.5 Instant 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 cheaper model fast.
Cost Comparison (1000 input + 500 output tokens, 100 requests/day)
GPT-5.5 Instant
Grok Code Fast 1
Cost Differences
Grok Code Fast 1 costs less than GPT-5.5 Instant
Quick Recommendation
Winner for direct API pricing: Grok Code Fast 1. At the default workload, Grok Code Fast 1 saves about $57.15/month ($695.325/year) versus GPT-5.5 Instant.
Feature Comparison
| Feature | GPT-5.5 Instant | Grok Code Fast 1 |
|---|---|---|
| Provider | OpenAI | xAI |
| Input Price | $5.00/1M tokens | $0.20/1M tokens |
| Output Price | $30.00/1M tokens | $1.50/1M tokens |
| Context Window | 1,050,000 tokens | 256,000 tokens |
| Max Output | 128,000 tokens | 32,768 tokens |
| Category | flagship | standard |
| Capabilities | textvisioncodereasoning | textcodereasoning |
| Release Date | 5/5/2026 | 2/1/2026 |
GPT-5.5 Instant vs Grok Code Fast 1: Which Should You Choose?
Choosing between GPT-5.5 Instant and Grok Code Fast 1 depends on your priorities: cost efficiency, context length, or raw capability. Grok Code Fast 1 is the more affordable option at $0.20/1M input tokens — 96% cheaper than GPT-5.5 Instant. Meanwhile, GPT-5.5 Instant offers a significantly larger context window at 1,050,000 tokens vs 256,000 for Grok Code Fast 1.
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 Instant is a flagship model while Grok Code Fast 1 is standard. This means they're optimized for different workloads. GPT-5.5 Instant is built for complex tasks that require deeper reasoning, while Grok Code Fast 1 offers better value for routine operations.
Output costs matter too. GPT-5.5 Instant charges $30.00/1M output tokens vs $1.50 for Grok Code Fast 1. For generation-heavy workloads (content creation, code generation, summarization), output pricing often dominates your bill. Grok Code Fast 1 has the edge here at $1.50/1M output tokens.
Multimodal capabilities: GPT-5.5 Instant supports vision (image inputs) while Grok Code Fast 1 is text-only. If your application needs image understanding, this narrows your choice.
Best Use Cases
Choose GPT-5.5 Instant when:
- • You need a larger context window (1,050,000 tokens)
- • You need more capabilities (vision)
- • You need longer outputs (up to 128,000 tokens)
- • You're already using OpenAI's API ecosystem
Choose Grok Code Fast 1 when:
- • Budget is a primary concern
- • You're already using xAI's API ecosystem
Pros and Caveats at a Glance
GPT-5.5 Instant
- • 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 Code Fast 1
- • Higher output cost than Grok Code Fast 1
Grok Code Fast 1
- • Input pricing: $0.20/M tokens
- • Output pricing: $1.50/M tokens
- • Context window: 256,000 tokens
- • Max output: 32,768 tokens
Watch out for
- • Smaller context window than GPT-5.5 Instant
Try Different Scenarios
Use the calculator below to see how costs change with different usage patterns
GPT-5.5 Instant (OpenAI)
Grok Code Fast 1 (xAI)
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Sign Up for xAI →Frequently Asked Questions
Which is cheaper, GPT-5.5 Instant or Grok Code Fast 1?▼
What is the context window difference between GPT-5.5 Instant and Grok Code Fast 1?▼
Which model is better for AI Agent / Agentic Workflows?▼
Which model has better overall pricing for heavy usage?▼
Where can I compare OpenAI and xAI API pricing beyond this model matchup?▼
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