Claude Sonnet 4.5
Last updated: April 22, 2026
Specs
| Vendor | Anthropic |
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| Released | June 12, 2025 |
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| Context window | 200K tokens |
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| Input | $3 / M tokens |
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| Output | $15 / M tokens |
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Benchmarks
| mmlu | 86.9 |
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| gpqa | 56.2 |
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| humanEval | 86.1 |
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| arenaElo | 1332 |
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| sweBench | 58 |
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| sweBenchPro | 50 |
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| liveCodeBench | 68 |
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| aiderPolyglot | 70 |
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| terminalBench | 40 |
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| mmluPro | 78 |
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| hle | 14 |
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| aime | 76 |
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| math500 | 92 |
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| mmmu | 72 |
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Strengths
- Cheaper than Opus 4.6 with very close quality
- Still the most integrated Sonnet in third-party tooling
- Predictable latency on Anthropic infra
Weaknesses
- Behind Sonnet 4.6 on coding and tool use
- Same 200K context: no gain on long-doc workloads
Best for
- Projects already in production on Sonnet 4.5
- Customers waiting to validate Sonnet 4.6 before upgrade
- Benchmark baselines for migration decisions
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