GPT 5.1 Chat

Chat Completions

gpt-5.1-chat

OpenAI|Created Nov 13, 2025|128k context

Chat Completions

GPT-5.1 Chat (also known as 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 harder queries, improving accuracy on math, coding, and multi-step tasks without slowing down typical conversations. The model is warmer and more conversational by default, with better instruction following and more stable short-form reasoning. GPT-5.1 Chat is designed for high-throughput, interactive workloads where responsiveness and consistency matter more than deep deliberation.

Overview Specifications Activity Performance Uptime Examples API Reference

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Pricing-50%

Pay-as-you-go rates for this model. More details can be found here.

Input Tokens (1M)

$0.63

Cached Input Tokens (1M)

$0.06

Output Tokens (1M)

$5.00

Capabilities

Input Modalities

TextImageFile

Output Modalities

Text

Supported Parameters

Available parameters for API requests

Frequency PenaltyFunction CallFunctionsLogit BiasMax Completion TokensParallel Tool CallsPredictionPresence PenaltyReasoning EffortResponse FormatStopTool ChoiceToolsWeb Search Options

Usage Analytics

Token usage of this model on our platform

Throughput

Not enough throughput data

Time-To-First-Token (TTFT)

Not enough TTFT data

Code Example

Example code for using this model through our API with Python (OpenAI SDK) or cURL. Replace placeholders with your API key and model ID.

Basic request example. Ensure API key permissions. For more details, see our documentation.

from openai import OpenAI

client = OpenAI(
    base_url="https://api.naga.ac/v1",
    api_key="YOUR_API_KEY",
)

resp = client.chat.completions.create(
    model="gpt-5.1-chat",
    messages=[
        {"role": "user", "content": "What's 2+2?"}
    ],
    temperature=0.2,
)
print(resp.choices[0].message.content)