GPT-5 Pro vs Llama 3.1 405B
GPT-5 Pro vs Llama 3.1 405B: Llama 3.1 405B is cheaper for input-heavy usage ($3.50/M vs $15.00/M input tokens), while GPT-5 Pro is better for long-context tasks (200,000 tokens).
Direct answer: choose Llama 3.1 405B for lower token spend and choose GPT-5 Pro 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)
GPT-5 Pro
Llama 3.1 405B
Cost Differences
Llama 3.1 405B costs less than GPT-5 Pro
Quick Recommendation
Winner for direct API pricing: Llama 3.1 405B. At the default workload, Llama 3.1 405B saves about $209.25/month ($2,545.875/year) versus GPT-5 Pro.
Feature Comparison
| Feature | GPT-5 Pro | Llama 3.1 405B |
|---|---|---|
| Provider | OpenAI | Meta (via Together AI) |
| Input Price | $15.00/1M tokens | $3.50/1M tokens |
| Output Price | $120.00/1M tokens | $3.50/1M tokens |
| Context Window | 200,000 tokens | 128,000 tokens |
| Max Output | 100,000 tokens | 32,768 tokens |
| Category | flagship | flagship |
| Capabilities | textvisioncodereasoning | textcodereasoning |
| Release Date | 8/7/2025 | 7/23/2024 |
GPT-5 Pro vs Llama 3.1 405B: Which Should You Choose?
Choosing between GPT-5 Pro and Llama 3.1 405B depends on your priorities: cost efficiency, context length, or raw capability. Llama 3.1 405B is the more affordable option at $3.50/1M input tokens — 77% cheaper than GPT-5 Pro. Meanwhile, GPT-5 Pro offers a significantly larger context window at 200,000 tokens vs 128,000 for Llama 3.1 405B.
These models come from different providers — OpenAI and Meta (via Together AI) — which means different API ecosystems, SDKs, rate limits, and terms of service. If you're already integrated with OpenAI, switching to Meta (via Together AI)involves migration effort beyond just pricing. Factor in your existing infrastructure when deciding.
Both models are in the flagship category, making this a direct head-to-head comparison. At scale — say 10,000 requests per day — the cost difference adds up: Llama 3.1 405B would save you roughly $20,925.00/month compared to GPT-5 Pro. For startups and indie developers, that difference can be significant.
Output costs matter too. GPT-5 Pro charges $120.00/1M 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. Llama 3.1 405B has the edge here at $3.50/1M output tokens.
Multimodal capabilities: GPT-5 Pro supports vision (image inputs) while Llama 3.1 405B is text-only. If your application needs image understanding, this narrows your choice.
Best Use Cases
Choose GPT-5 Pro when:
- • You need a larger context window (200,000 tokens)
- • You need more capabilities (vision)
- • You need longer outputs (up to 100,000 tokens)
- • You're already using OpenAI's API ecosystem
Choose Llama 3.1 405B when:
- • Budget is a primary concern
- • You're already using Meta (via Together AI)'s API ecosystem
Pros and Caveats at a Glance
GPT-5 Pro
- • Input pricing: $15.00/M tokens
- • Output pricing: $120.00/M tokens
- • Context window: 200,000 tokens
- • Max output: 100,000 tokens
Watch out for
- • Higher input cost than Llama 3.1 405B
- • Higher output cost than Llama 3.1 405B
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
- • Smaller context window than GPT-5 Pro
Try Different Scenarios
Use the calculator below to see how costs change with different usage patterns
GPT-5 Pro (OpenAI)
Llama 3.1 405B (Meta (via Together AI))
Start using GPT-5 Pro today
Sign Up for OpenAI →Start using Llama 3.1 405B today
Sign Up for Meta (via Together AI) →Frequently Asked Questions
Which is cheaper, GPT-5 Pro or Llama 3.1 405B?▼
What is the context window difference between GPT-5 Pro 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 OpenAI and Meta (via Together AI) API pricing beyond this model matchup?▼
Related Comparisons
Related Articles
Learn when to pick each model, then compare live pricing scenarios.