GPT-5.3 Codex vs Grok 4.1 Fast
Compare OpenAI and xAI AI models
Cost Comparison (1000 input + 500 output tokens, 100 requests/day)
GPT-5.3 Codex
Grok 4.1 Fast
Cost Differences
Grok 4.1 Fast costs less than GPT-5.3 Codex
Feature Comparison
| Feature | GPT-5.3 Codex | Grok 4.1 Fast |
|---|---|---|
| Provider | OpenAI | xAI |
| Input Price | $1.75/1M tokens | $0.20/1M tokens |
| Output Price | $14.00/1M tokens | $0.50/1M tokens |
| Context Window | 256,000 tokens | 2,000,000 tokens |
| Max Output | 32,768 tokens | 131,072 tokens |
| Category | coding | efficient |
| Capabilities | textcode | textreasoningcode |
| Release Date | 3/1/2026 | 1/15/2026 |
GPT-5.3 Codex vs Grok 4.1 Fast: Which Should You Choose?
Choosing between GPT-5.3 Codex 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 — 89% cheaper than GPT-5.3 Codex. Meanwhile, Grok 4.1 Fast offers a significantly larger context window at 2,000,000 tokens vs 256,000 for GPT-5.3 Codex.
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-5.3 Codex is a coding model while Grok 4.1 Fast is efficient. This means they're optimized for different workloads. Grok 4.1 Fast targets more demanding workloads, while GPT-5.3 Codex provides a cost-effective option for everyday tasks.
Output costs matter too. GPT-5.3 Codex charges $14.00/1M 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.
Best Use Cases
Choose GPT-5.3 Codex when:
- • 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 more capabilities (reasoning)
- • 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
Try Different Scenarios
Use the calculator below to see how costs change with different usage patterns
GPT-5.3 Codex (OpenAI)
Grok 4.1 Fast (xAI)
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