GPT-3.5 Turbo Instruct vs GPT-5.1 Chat
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 Instruct and GPT-5.1 Chat.
GPT-3.5 Turbo Instruct
This model is a variant of GPT-3.5 Turbo tuned for instructional prompts and omitting chat-related optimizations. Training data: up to Sep 2021.
GPT-5.1 Chat
GPT-5.1 Chat (AKA Instant is the fast, lightweight member of the 5.1 family, optimized for low-latency chat while retaining strong general intelligence. It uses adaptive reasoning to selectively “think” on...
Technical Specifications
| Specification | GPT-3.5 Turbo Instruct | GPT-5.1 Chat |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Context Window | 4,095 tokens | 128,000 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 | 2023-09-28 | 2025-11-13 |
API Pricing Comparison
Input Price per Million Tokens
GPT-3.5 Turbo Instruct
$1.50
GPT-5.1 Chat
$1.25
Output Price per Million Tokens
GPT-3.5 Turbo Instruct
$2.00
GPT-5.1 Chat
$10.00
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 Instruct Quirks & Gotchas
No developer gotchas reported.
GPT-5.1 Chat Quirks & Gotchas
No developer gotchas reported.