GPT-5.5 Pro vs GPT-5.6 Terra
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 GPT-5.5 Pro and GPT-5.6 Terra.
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...
GPT-5.6 Terra
GPT-5.6 Terra is a balanced model in OpenAI's GPT-5.6 series, positioned between the flagship Sol tier and the cost-efficient Luna tier. It is suited for everyday coding, reasoning, and agentic...
Technical Specifications
| Specification | GPT-5.5 Pro | GPT-5.6 Terra |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Context Window | 1,050,000 tokens | 1,050,000 tokens |
| Agent Suitability | 98/100 | N/A |
| Time to First Token (TTFT) | 450 ms | N/A |
| Deployment Model | managed api | managed api |
| Production Stability | beta | beta |
| API Available | Yes | Yes |
| Released Date | 2026-04-24 | 2026-07-09 |
API Pricing Comparison
Input Price per Million Tokens
GPT-5.5 Pro
$30.00
GPT-5.6 Terra
$2.50
Output Price per Million Tokens
GPT-5.5 Pro
$180.00
GPT-5.6 Terra
$15.00
Want to test both models live?
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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.
GPT-5.5 Pro Quirks & Gotchas
- ▸Best-in-class instruction following for complex agentic chains
- ▸Premium pricing — use GPT-5 for cost-sensitive workloads
GPT-5.6 Terra Quirks & Gotchas
No developer gotchas reported.