GPT-5.1 Chat API
About
Build advanced reasoning agents with GPT-5.1 Chat, a specialized AI model optimized for complex logic and chain-of-thought tasks. This model delivers cost-effective pricing at $1.25/1M input and $10.00/1M output tokens, native tool calling support. Access GPT-5.1 Chat via the Merge Gateway API with up to 16K output tokens.
Capabilities
Input Modalities
textimage
Output Modalities
text
Reasoning
Yes
Structured Output
Limits
Context Window
128K
Tokens
Input Limit
128K
Tokens
Max Output
16K
Tokens
Pricing
Standard (per 1M tokens)
Input
$1.25
Output
$10.00
Caching (per 1M tokens)
Read
$0.13
Frequently Asked Questions
GPT-5.1 Chat by Merge Gateway costs $1.25 per 1M input tokens and $10.00 per 1M output tokens. Cached reads cost $0.13 per 1M tokens.
Model Details
ID
openai/gpt-5.1-chat-latest
Provider
Merge GatewayFamily
gpt-codex
Release Date
Nov 13, 2025
Knowledge Cutoff
Sep 30, 2024
API Integration