Claude Sonnet 4.5 vs DeepSeek V3.1 Terminus
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 4.5 and DeepSeek V3.1 Terminus.
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...
DeepSeek V3.1 Terminus
DeepSeek-V3.1 Terminus is an update to [DeepSeek V3.1](/deepseek/deepseek-chat-v3.1) that maintains the model's original capabilities while addressing issues reported by users, including language consistency and agent capabilities, further optimizing the model's...
Technical Specifications
| Specification | Claude Sonnet 4.5 | DeepSeek V3.1 Terminus |
|---|---|---|
| Provider | Anthropic | DeepSeek |
| Context Window | 1,000,000 tokens | 163,840 tokens |
| Agent Suitability | 91/100 | N/A |
| Time to First Token (TTFT) | 380 ms | N/A |
| Deployment Model | managed api | self hostable |
| Production Stability | stable | stable |
| API Available | Yes | Yes |
| Released Date | 2025-09-29 | 2025-09-22 |
API Pricing Comparison
Input Price per Million Tokens
Claude Sonnet 4.5
$3.00
DeepSeek V3.1 Terminus
$0.27
Output Price per Million Tokens
Claude Sonnet 4.5
$15.00
DeepSeek V3.1 Terminus
$0.95
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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 4.5 Quirks & Gotchas
- ▸Excellent for long-form writing and nuanced document analysis
- ▸Slightly slower than Sonnet 4.6 — upgrade for production agentic use
DeepSeek V3.1 Terminus Quirks & Gotchas
No developer gotchas reported.