Claude Opus 4.5 vs Llama 3.1 405B
Anthropic vs Meta · Prices checked 12 August 2026
There is a 41.3× price gap here. Llama 3.1 405B blends to $0.800 per million tokens; Claude Opus 4.5 to $33.00. A single 100K-input, 10K-output job costs $0.088 on Llama 3.1 405B against $2.25 on Claude Opus 4.5.
Capability favours Claude Opus 4.5, ahead on 4 of 5 suites they both publish. The widest gap is on LMArena Elo, where Claude Opus 4.5 leads by 76 points. Claude Opus 4.5 reads more in one request: 200,000 tokens of context against 128,000.
Pricing and capacity
| Metric | Claude Opus 4.5 | Llama 3.1 405B | Difference |
|---|---|---|---|
| Input / 1M tokens | $15.00 | $0.800 | 18.8× |
| Output / 1M tokens | $75.00 | $0.800 | 93.8× |
| Blended · 70/30calculated | $33.00 | $0.800 | 41.3× |
| Blended · 50/50calculated | $45.00 | $0.800 | 56.3× |
| Blended · 80/20calculated | $27.00 | $0.800 | 33.7× |
| Blended · 20/80calculated | $63.00 | $0.800 | 78.7× |
| Job cost · 100K + 10Kcalculated | $2.25 | $0.088 | 25.6× |
| Job cost · 1M + 100Kcalculated | $22.50 | $0.880 | 25.6× |
| Context window | 200,000 | 128,000 | 36% |
Input and output rates are as published by each provider. Blended and job-cost rows are calculated comparison metrics, not published prices — how they are derived.
Benchmarks
| Benchmark | Claude Opus 4.5 | Llama 3.1 405B | Leader |
|---|---|---|---|
| MMLU | 87% | 88% | Llama 3.1 405B |
| GPQA Diamond | 76% | 51% | Claude Opus 4.5 |
| MATH | 88% | 73% | Claude Opus 4.5 |
| HumanEval | 93% | 89% | Claude Opus 4.5 |
| LMArena Elo | 1366 Elo | 1290 Elo | Claude Opus 4.5 |
Only suites both models report are listed, so a missing score is never shown as a loss. Figures are provider-published or from public leaderboards and are not independently re-run.
What each model is for
Claude Opus 4.5
Anthropic · Previous
Direct predecessor to Opus 4.6. Strong choice when you need Claude 4 behaviour without changing existing prompts and evals tuned to the 4.5 generation.
- 1M-token context
- Stable for production pipelines
- Strong agentic coding
- Tool use & function calling
Llama 3.1 405B
Meta · Large
Largest dense Llama. Used as a quality benchmark for open weights, heavy to run, often hosted via Together / DeepInfra / Cerebras.
- Top open-weights quality
- Permissive license
- Strong reasoning
Frequently asked questions
Which is cheaper, Claude Opus 4.5 or Llama 3.1 405B?
There is a 41.3× price gap here. Llama 3.1 405B blends to $0.800 per million tokens; Claude Opus 4.5 to $33.00. A single 100K-input, 10K-output job costs $0.088 on Llama 3.1 405B against $2.25 on Claude Opus 4.5. Blended cost weights input at 70% and output at 30%; price your own token split for an exact answer, since the cheaper model on a blended basis is not always cheaper for your workload.
Which performs better, Claude Opus 4.5 or Llama 3.1 405B?
Capability favours Claude Opus 4.5, ahead on 4 of 5 suites they both publish. The widest gap is on LMArena Elo, where Claude Opus 4.5 leads by 76 points. These are the figures each provider or public leaderboard publishes, not results we re-run, and a benchmark average can hide the specific behaviour your workload depends on.
Which has the larger context window, Claude Opus 4.5 or Llama 3.1 405B?
Claude Opus 4.5 reads more in one request: 200,000 tokens of context against 128,000. The context window caps everything in a single request: prompt, retrieved documents, conversation history and the model’s own output all share it.
Can I compare Claude Opus 4.5 and Llama 3.1 405B on my own numbers?
Yes. Open both in the side-by-side comparison tool to see every field at once, or use the token calculator to price your actual prompt and monthly request volume against each model. Both are free and need no sign-up.
Price it for your own workload
Related matchups
Terms used on this page
Prices and scores are recomputed on every deploy from the catalogue. Prices checked 12 August 2026.