GPT-4o 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-4o and GPT-5.1 Chat.
GPT-4o
GPT-4o ("o" for "omni") is OpenAI's latest AI model, supporting both text and image inputs with text outputs. It maintains the intelligence level of [GPT-4 Turbo](/models/openai/gpt-4-turbo) while being twice as...
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-4o | GPT-5.1 Chat |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Context Window | 128,000 tokens | 128,000 tokens |
| Agent Suitability | 90/100 | N/A |
| Time to First Token (TTFT) | 280 ms | N/A |
| Deployment Model | managed api | managed api |
| Production Stability | stable | stable |
| API Available | Yes | Yes |
| Released Date | 2024-05-13 | 2025-11-13 |
API Pricing Comparison
Input Price per Million Tokens
GPT-4o
$2.50
GPT-5.1 Chat
$1.25
Output Price per Million Tokens
GPT-4o
$10.00
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-4o Quirks & Gotchas
- ▸Strong multimodal performance — best vision+tool calling combo
- ▸Legacy model — migrate to GPT-5 for latest improvements
GPT-5.1 Chat Quirks & Gotchas
No developer gotchas reported.