Claude Sonnet 4.5 Reasoning: pricing, context window and benchmarks
Claude Sonnet 4.5 Reasoning is a frontier model from Anthropic. It offers a 400,000-token context window, costs $19.48 per million input tokens and $68.20 per million output tokens, and averages 87.7 across the index's benchmark suite.
Pricing
Claude Sonnet 4.5 Reasoning costs $19.48 per million input tokens and $68.20 per million output tokens. A blended 3:1 input-to-output mix works out to about $31.66 per million tokens. Cached input is listed at $1.58 per million tokens.
| Item | Price | Notes |
|---|---|---|
| Input | $19.48 | per 1M tokens |
| Output | $68.20 | per 1M tokens |
| Cached input | $1.58 | per 1M tokens |
| Blended 3:1 | $31.66 | estimate per 1M tokens |
| 1M in + 1M out | $87.68 | estimate |
Benchmarks
Scores below are modelled estimates on a 0–100 scale. Use them to compare relative position, not as official vendor results.
| Benchmark | Score | Rank | Percentile | Relative |
|---|---|---|---|---|
| MMLU-Pro | 87.6 | 24 | 96th | |
| GPQA Diamond | 85.2 | 5 | 99th | |
| SWE-bench Verified | 79.6 | 8 | 99th | |
| HumanEval | 90.3 | 40 | 93th | |
| MATH-500 | 89.7 | 51 | 92th | |
| AIME 2025 | 87.3 | 17 | 97th | |
| LiveCodeBench | 85.1 | 1 | 100th | |
| IFEval | 91.9 | 41 | 93th | |
| TruthfulQA | 87.6 | 26 | 96th | |
| HellaSwag | 95.2 | 5 | 99th | |
| MMMU | 85.2 | 4 | 99th | |
| Arena Elo | 1486.5 | 12 | 98th |
What Claude Sonnet 4.5 Reasoning is good for
Claude Sonnet 4.5 Reasoning sits in the frontier tier of the index. It is aimed at work where answer quality matters more than unit cost: hard reasoning, multi-step coding, document analysis and multimodal inputs. At $19.48 per million input tokens and a 400,000-token context window, it is a premium option, so reserve it for tasks where a cheaper model measurably fails.
Strengths
- Top-tier average benchmark score (87.7), placing it #13 of 600.
- Large 400,000-token context window for long documents and agent traces.
- Accepts more than text, including image input where the provider supports it.
- Reasoning-oriented profile, useful for multi-step problems and structured analysis.
- Coding benchmarks are a relative strength within its tier.
Trade-offs
- Proprietary licence: you cannot download the weights or self-host the model.
- Premium input pricing at $19.48 per million tokens.
- Cost can climb quickly on long outputs and high-volume traffic.
How it compares
| Model | Provider | Context | Input / 1M | Avg score |
|---|---|---|---|---|
| GPT-5.1 Max | OpenAI | 2000000 | $20.50 | 87.9 |
| Claude Opus 4.5 Max | Anthropic | 1000000 | $20.90 | 87.8 |
| GPT-5.1 Pro | OpenAI | 200000 | $19.77 | 87.8 |
| Grok 4 Reasoning | xAI | 2000000 | $19.67 | 87.8 |
| Claude Opus 4.5 | Anthropic | 400000 | $19.42 | 87.7 |
| Claude Sonnet 4.5 Reasoning | Anthropic | 400000 | $19.48 | 87.7 |
FAQ
How much does Claude Sonnet 4.5 Reasoning cost?
Claude Sonnet 4.5 Reasoning is listed at $19.48 per million input tokens and $68.20 per million output tokens. Cached input is $1.58 per million tokens. A blended 3:1 input-to-output mix is about $31.66 per million tokens.
What is the context window of Claude Sonnet 4.5 Reasoning?
Claude Sonnet 4.5 Reasoning has a context window of 400,000 tokens and can emit up to 8,192 output tokens per request in this index.
Is Claude Sonnet 4.5 Reasoning open weights?
No. Claude Sonnet 4.5 Reasoning is a proprietary model with a proprietary licence, so you cannot download the weights.
How does Claude Sonnet 4.5 Reasoning score on benchmarks?
Claude Sonnet 4.5 Reasoning averages 87.7 across the scored benchmarks in this index, ranking #13 of 600 models. Its strongest relative result is LiveCodeBench at 85.1.
What is Claude Sonnet 4.5 Reasoning best for?
Claude Sonnet 4.5 Reasoning sits in the frontier tier of the index. It is aimed at work where answer quality matters more than unit cost: hard reasoning, multi-step coding, document analysis and multimodal inputs. At $19.48 per million input tokens and a 400,000-token context window, it is a premium option, so reserve it for tasks where a cheaper model measurably fails.