Grok 4.1 Fast vs Llama 3.1 405B
Grok 4.1 Fast vs Llama 3.1 405B: Grok 4.1 Fast is cheaper for input-heavy usage ($0.20/M vs $3.50/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.
Compare input and output token pricing, context windows, and monthly cost estimates on one page so you can pick the cheaper model fast.
Cost Comparison (1000 input + 500 output tokens, 100 requests/day)
Grok 4.1 Fast
Llama 3.1 405B
Cost Differences
Llama 3.1 405B costs more than Grok 4.1 Fast
Quick Recommendation
Winner for direct API pricing: Grok 4.1 Fast. At the default workload, Grok 4.1 Fast saves about $14.40/month ($175.20/year) versus Llama 3.1 405B.
Feature Comparison
| Feature | Grok 4.1 Fast | Llama 3.1 405B |
|---|---|---|
| Provider | xAI | Meta (via Together AI) |
| Input Price | $0.20/1M tokens | $3.50/1M tokens |
| Output Price | $0.50/1M tokens | $3.50/1M tokens |
| Context Window | 2,000,000 tokens | 128,000 tokens |
| Max Output | 131,072 tokens | 32,768 tokens |
| Category | efficient | flagship |
| Capabilities | textreasoningcode | textcodereasoning |
| Release Date | 1/15/2026 | 7/23/2024 |
Grok 4.1 Fast vs Llama 3.1 405B: Which Should You Choose?
Choosing between Grok 4.1 Fast and Llama 3.1 405B 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 — 94% cheaper than Llama 3.1 405B. Meanwhile, Grok 4.1 Fast offers a significantly larger context window at 2,000,000 tokens vs 128,000 for Llama 3.1 405B.
These models come from different providers — xAI and Meta (via Together AI) — which means different API ecosystems, SDKs, rate limits, and terms of service. If you're already integrated with xAI, switching to Meta (via Together AI)involves migration effort beyond just pricing. Factor in your existing infrastructure when deciding.
These models target different tiers: Grok 4.1 Fast is a efficient model while Llama 3.1 405B is flagship. This means they're optimized for different workloads. Llama 3.1 405B targets more demanding workloads, while Grok 4.1 Fast provides a cost-effective option for everyday tasks.
Output costs matter too. Grok 4.1 Fast charges $0.50/1M output tokens vs $3.50 for Llama 3.1 405B. 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 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
Choose Llama 3.1 405B when:
- • You're already using Meta (via Together AI)'s API ecosystem
Pros and Caveats at a Glance
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.
Llama 3.1 405B
- • Input pricing: $3.50/M tokens
- • Output pricing: $3.50/M tokens
- • Context window: 128,000 tokens
- • Max output: 32,768 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
Try Different Scenarios
Use the calculator below to see how costs change with different usage patterns
Grok 4.1 Fast (xAI)
Llama 3.1 405B (Meta (via Together AI))
Start using Grok 4.1 Fast today
Sign Up for xAI →Start using Llama 3.1 405B today
Sign Up for Meta (via Together AI) →Frequently Asked Questions
Which is cheaper, Grok 4.1 Fast or Llama 3.1 405B?▼
What is the context window difference between Grok 4.1 Fast and Llama 3.1 405B?▼
Which model is better for AI Agent / Agentic Workflows?▼
Which model has better overall pricing for heavy usage?▼
Where can I compare xAI and Meta (via Together AI) API pricing beyond this model matchup?▼
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