GPT-5.1: Complete Specifications, Pricing, API Access & Use Cases (2026)
GPT-5.1 is an OpenAI reasoning model designed for general assistants, coding, document analysis, tool use, and agentic workflows. Released on November 13, 2025, it adjusts reasoning depth to task difficulty, answering simple prompts quickly while spending more time on complex problems. This guide covers its specifications, pricing, modalities, production strengths, limitations, comparisons, and Gate.AI access as reviewed in July 2026.
What is GPT-5.1?
GPT-5.1 succeeds GPT-5 within OpenAI’s general-purpose model family. Its defining feature is adaptive reasoning: the model can use lighter deliberation for routine requests and deeper reasoning for difficult analysis, planning, coding, or tool-based tasks.
The standard GPT-5.1 model is different from gpt-5.1-chat-latest , which targeted conversational use, and from GPT-5.1-Codex variants built for longer autonomous coding sessions. The base model is broader, supporting mixed workloads such as document review, structured output, code generation, tool calls, and multi-step automation.
GPT-5.1 was later removed from ChatGPT, but ChatGPT retirement does not automatically confirm removal from third-party API catalogs. Availability through Gate.AI should therefore be checked against the current model listing.
What Are GPT-5.1’s Key Specifications and Pricing?
As per the Gate.AI model-card, GPT-5.1 is listed with a 400K-token context window and model ID openai/gpt-5.1 .
| Specification | Listed Value |
|---|---|
| Provider | OpenAI |
| Release date | November 13, 2025 |
| Context window | 400K tokens |
| Model ID | openai/gpt-5.1 |
| Input price | $1.25 per million tokens |
| Output price | $10 per million tokens |
| Cached input | $0.13 per million tokens |
| Cache write | Not listed |
For a request using 100,000 uncached input tokens and 20,000 output tokens, the estimated listed cost is:
( 100,000 ÷ 1,000,000 × $1.25) + (20,000 ÷ 1,000,000 × $10) = $ 0.325
This calculation excludes account-specific pricing, routing adjustments, and other platform charges. Because output tokens cost more than input tokens, concise response limits can materially reduce spending.
What Can GPT-5.1 Do That Makes It Useful in Production?
GPT-5.1 is useful when one application must handle both easy and difficult tasks. A support assistant may answer a simple account question quickly, then apply deeper reasoning to a complex troubleshooting request without switching models.
For coding, it can interpret requirements, generate functions, explain changes, review patches, and coordinate tool calls. Teams building more autonomous coding systems may also compare it with GPT-5.1-Codex , which is positioned for longer edit-debug-refactor workflows.
Its 400K context window can support long policies, codebases, logs, or research documents. However, placing more information into a prompt does not guarantee equal attention to every section. Retrieval, chunking, citation checks, and output validation remain important.
A practical decision rule is to use lower reasoning for classification, rewriting, extraction, or formatting, and higher reasoning for ambiguous planning, debugging, or multi-tool tasks. This helps balance latency, quality, and token use.
What Are GPT-5.1’s Supported Modalities?
| Modality | Input | Output | Practical Note |
|---|---|---|---|
| Text | Yes | Yes | Main interface for prompts, code, and documents |
| Images | Supported where exposed | No | Vision depends on the selected API route |
| Audio | Not confirmed | No | Use a dedicated speech model |
| Video | Not confirmed | No | Use a specialized video model |
| Structured data | Yes | Yes | JSON or schema controls depend on the platform |
| Tool calls | Yes | Yes | External execution must be handled by the application |
GPT-5.1 should be treated primarily as a text-output reasoning model. It is not an image, audio, or video generator. Modality support must be verified for the exact Gate.AI route rather than inferred from the wider GPT family.
Where Does GPT-5.1 Fall Short?
GPT-5.1 is no longer OpenAI’s newest general-purpose model. Teams starting new deployments should compare it with later models such as GPT-5.2 Pro or GPT-5.4 .
Its listed output price is eight times its uncached-input price, so applications producing long answers may become output-cost heavy. Adaptive reasoning can also create variable latency because harder prompts may require more computation.
A large context window does not eliminate hallucination, weak source use, insecure code, or unsupported conclusions. Human review remains necessary for legal, medical, financial, security-sensitive, and other high-impact workflows.
What Is GPT-5.1 Best Used For?
GPT-5.1 is well suited to general assistants, coding copilots, document intelligence, structured analysis, and tool-enabled automation. It fits teams that want one model to cover routine prompts and difficult reasoning requests at moderate listed token prices.
Choose GPT-5.1 when adaptive reasoning, coding, tool use, and long-context processing matter. Consider GPT-4o Mini for cheaper high-volume tasks, a Codex model for long-running software agents, or a newer GPT generation when improved capability justifies higher cost.
How Does GPT-5.1 Compare to GPT-5 and GPT-5.2?
| Dimension | GPT-5 | GPT-5.1 | GPT-5.2 |
|---|---|---|---|
| Position | Earlier flagship | Adaptive-reasoning successor | Newer successor |
| Main focus | General reasoning and coding | Balanced speed, reasoning, coding, agents | Improved intelligence and context handling |
| Input price | $1.25/M | $1.25/M | $1.75/M |
| Output price | $10/M | $10/M | $14/M |
| Best fit | Existing GPT-5 workloads | Cost-balanced mixed workloads | Teams prioritizing later-generation capability |
GPT-5.1 is attractive when its pricing and adaptive reasoning fit an existing workflow. GPT-5.2 may suit teams willing to pay more for newer capability, while GPT-5 remains relevant mainly to established deployments. This distinction matters when teams estimate migration effort, latency expectations, and maintenance costs.
How Do I Access GPT-5.1 Through Gate.AI?
Gate.AI provides an OpenAI-compatible route using the base URL https://api.gate.ai/openai/v1 . Store the API key in an environment variable and use the listed model ID.
Python
Python import os
import OpenAI from openai
api_key = os.getenv("GATEAI_API_KEY")
if not api_key:
raise RuntimeError("Set GATEAI_API_KEY first.")
client = OpenAI(
api_key=api_key,
base_url="https://api.gate.ai/openai/v1",
)
response = client.chat.completions.create(
model="openai/gpt-5.1",
messages=[
{
"role": "user",
"content": "Explain adaptive reasoning briefly."
}
],
)
print(response.choices[0].message.content) ```
curl
``` Bash curl https://api.gate.ai/openai/v1/chat/completions \
-H "Authorization: Bearer $GATEAI_API_KEY" \
-H "Content-Type: application/json" \
-d ‘{
"model": "openai/gpt-5.1",
"messages": [
{
"role": "user",
"content": "Explain adaptive reasoning briefly."
}
]
}’ ```
These examples follow the documented OpenAI-compatible pattern but were not execution-tested. Confirm current availability, model ID, supported parameters, and pricing in the live Gate.AI catalog before production use.
FAQs
When was GPT-5.1 released?
OpenAI released GPT-5.1 on November 13, 2025.
What is GPT-5.1’s context window?
As per the Gate.AI listing, GPT-5.1 supports a 400K-token context window.
How much does GPT-5.1 cost?
The Gate.AI model-card lists $ 1.25 per million input tokens, $ 10 per million output tokens, and $ 0.13 per million cached-input tokens.
Is GPT-5.1 a coding model?
It supports coding, debugging, tool use, and structured development workflows, but it is a general-purpose model rather than a Codex-only variant.
Is GPT-5.1 still available?
It was retired from ChatGPT, but Gate.AI availability must be checked separately in the live catalog.
