Claude Sonnet 4 vs Claude Sonnet 4.5
How do these models stack up? Below is an expert side-by-side comparison of specifications, context window capacity, live pricing per million tokens, and standardized benchmark scores for Claude Sonnet 4 and Claude Sonnet 4.5.
Claude Sonnet 4
Claude Sonnet 4 significantly enhances the capabilities of its predecessor, Sonnet 3.7, excelling in both coding and reasoning tasks with improved precision and controllability. Achieving state-of-the-art performance on SWE-bench (72.7%),...
Claude Sonnet 4.5
Claude Sonnet 4.5 is Anthropic’s most advanced Sonnet model to date, optimized for real-world agents and coding workflows. It delivers state-of-the-art performance on coding benchmarks such as SWE-bench Verified, with...
Technical Specifications
| Specification | Claude Sonnet 4 | Claude Sonnet 4.5 |
|---|---|---|
| Provider | Anthropic | Anthropic |
| Context Window | 1,000,000 tokens | 1,000,000 tokens |
| Agent Suitability | N/A | 91/100 |
| Time to First Token (TTFT) | N/A | 380 ms |
| Deployment Model | managed api | managed api |
| Production Stability | beta | stable |
| API Available | Yes | Yes |
| Released Date | 2025-05-22 | 2025-09-29 |
API Pricing Comparison
Input Price per Million Tokens
Claude Sonnet 4
$3.00
Claude Sonnet 4.5
$3.00
Output Price per Million Tokens
Claude Sonnet 4
$15.00
Claude Sonnet 4.5
$15.00
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Benchmark Performance Metrics
Scores show the raw performance percentages verified across key evaluation suites. Higher bars indicate superior accuracy and capability in that domain.
Claude Sonnet 4 Quirks & Gotchas
No developer gotchas reported.
Claude Sonnet 4.5 Quirks & Gotchas
- ▸Excellent for long-form writing and nuanced document analysis
- ▸Slightly slower than Sonnet 4.6 — upgrade for production agentic use