DeepSeek V3.1 Terminus vs GPT-5.5 Pro
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 DeepSeek V3.1 Terminus and GPT-5.5 Pro.
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...
GPT-5.5 Pro
GPT-5.5 Pro is OpenAI’s high-capability model optimized for deep reasoning and accuracy on complex, high-stakes workloads. It features a 1M+ token context window (922K input, 128K output) with support for...
Technical Specifications
| Specification | DeepSeek V3.1 Terminus | GPT-5.5 Pro |
|---|---|---|
| Provider | DeepSeek | OpenAI |
| Context Window | 163,840 tokens | 1,050,000 tokens |
| Agent Suitability | N/A | 98/100 |
| Time to First Token (TTFT) | N/A | 450 ms |
| Deployment Model | self hostable | managed api |
| Production Stability | stable | beta |
| API Available | Yes | Yes |
| Released Date | 2025-09-22 | 2026-04-24 |
API Pricing Comparison
Input Price per Million Tokens
DeepSeek V3.1 Terminus
$0.27
GPT-5.5 Pro
$30.00
Output Price per Million Tokens
DeepSeek V3.1 Terminus
$0.95
GPT-5.5 Pro
$180.00
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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.
DeepSeek V3.1 Terminus Quirks & Gotchas
No developer gotchas reported.
GPT-5.5 Pro Quirks & Gotchas
- ▸Best-in-class instruction following for complex agentic chains
- ▸Premium pricing — use GPT-5 for cost-sensitive workloads