GPT-3.5 Turbo (older v0613) vs GPT-5.1-Codex
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-5.1-Codex.
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-5.1-Codex
GPT-5.1-Codex is a specialized version of GPT-5.1 optimized for software engineering and coding workflows. It is designed for both interactive development sessions and long, independent execution of complex engineering tasks....
Technical Specifications
| Specification | GPT-3.5 Turbo (older v0613) | GPT-5.1-Codex |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Context Window | 4,095 tokens | 400,000 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 | stable |
| API Available | Yes | Yes |
| Released Date | 2024-01-25 | 2025-11-13 |
API Pricing Comparison
Input Price per Million Tokens
GPT-3.5 Turbo (older v0613)
$1.00
GPT-5.1-Codex
$1.25
Output Price per Million Tokens
GPT-3.5 Turbo (older v0613)
$2.00
GPT-5.1-Codex
$10.00
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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.
GPT-3.5 Turbo (older v0613) Quirks & Gotchas
No developer gotchas reported.
GPT-5.1-Codex Quirks & Gotchas
No developer gotchas reported.