GPT-3.5 Turbo (older v0613) vs GPT-5.6 Terra 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 GPT-3.5 Turbo (older v0613) and GPT-5.6 Terra Pro.
GPT-3.5 Turbo (older v0613)
GPT-3.5 Turbo is OpenAI's fastest model. It can understand and generate natural language or code, and is optimized for chat and traditional completion tasks. Training data up to Sep 2021.
GPT-5.6 Terra Pro
GPT-5.6 Terra Pro is the same underlying model as [GPT-5.6 Terra](https://openrouter.ai/openai/gpt-5.6-terra), served with `reasoning.mode` set to `pro` for higher-quality responses on complex tasks. Learn more in OpenAI's docs: https://developers.openai.com/api/docs/guides/reasoning#reasoning-mode
Technical Specifications
| Specification | GPT-3.5 Turbo (older v0613) | GPT-5.6 Terra Pro |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Context Window | 4,095 tokens | 1,050,000 tokens |
| Agent Suitability | N/A | N/A |
| Time to First Token (TTFT) | N/A | N/A |
| Deployment Model | managed api | managed api |
| Production Stability | stable | beta |
| API Available | Yes | Yes |
| Released Date | 2024-01-25 | 2026-07-09 |
API Pricing Comparison
Input Price per Million Tokens
GPT-3.5 Turbo (older v0613)
$1.00
GPT-5.6 Terra Pro
$2.50
Output Price per Million Tokens
GPT-3.5 Turbo (older v0613)
$2.00
GPT-5.6 Terra Pro
$15.00
Want to test both models live?
Run side-by-side prompt prompts in our dynamic Sandbox. Check execution speeds, latency metrics, and compute actual costs in real-time.
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-3.5 Turbo (older v0613) Quirks & Gotchas
No developer gotchas reported.
GPT-5.6 Terra Pro Quirks & Gotchas
No developer gotchas reported.