GPT-5.1
gpt-5.1
OpenAI · chat · api
Intelligence
Context
272K
Max output
128K
Input $/1M
$1.25
Output $/1M
$10.00
Modalities
text
Released
10 Nov 2025
Intelligence Index via Artificial Analysis · 0–100, higher is better
AI summary
● machine-written
OpenAI releases GPT-5.1 with 400K context window and reasoning modes
GPT-5.1 is a chat model from OpenAI released in November 2025, available via API and ChatGPT interfaces. It features two operational modes—Instant for conversational responses and Thinking for deep reasoning—with a 400K token context window and 128K output token capacity. The model supports token-based pricing with standard and discounted tiers for different use cases.
What's new
- Two operational modes: GPT-5.1 Instant for fast responses and GPT-5.1 Thinking for adaptive reasoning
- Context window expanded to 400K tokens total (272K input / 128K output)
- Prompt caching offers 90% discount on cached input tokens
- Batch API processing available at 50% discount for non-urgent tasks
- Released November 13, 2025 via API with phased rollout to users
Best for
Document analysis and content processing with large context requirementsChatbots and customer service applications with repeated queriesComplex reasoning tasks requiring adaptive computational effortBatch processing and background tasks with cost optimization