GPT-5.1 is an efficient reasoning model from OpenAI, offering strong coding capabilities at a lower cost than GPT-5.2. It's optimized for responsive development workflows.

GPT-5.1 achieved SOTA on diff editing benchmarks with a 7% improvement. It's praised for being more deliberate with fewer wasted actions and better task focus.

GPT-5.1 excels at PR reviews, diff editing, front-end development, multi-file project iteration, and complex instruction following with reduced overthinking.

How is GPT-5.1 different from GPT-5.2?

GPT-5.1 is slightly less capable but cheaper than GPT-5.2, offering snappier responses and reduced overthinking for everyday coding tasks.

How much does GPT-5.1 cost?

GPT-5.1 API pricing is $1.25 per 1M input tokens and $10.00 per 1M output tokens. Cached input tokens cost $0.125 per 1M.

LangFast

Beta

GPT-5.1

Slightly weaker GPT-5.2, cheaper, still strong at reasoning.

Try in Playground

Community Sentiment

Mostly Positive

Based on Reddit reviews

Community Verdict

Best for Efficient Coding

Based on Reddit reviews

Input Modalities

Text, Images

Output Modalities

Text

Price / 1M tokens

$1.25$10

InputOutput

Best For

Efficient coding help without overthinking

PR reviews & diff edits (7% SOTA gain)

Frontend dev & functional UI design

Multi-file iteration & refactoring

Complex instruction handling

Snappy dev workflows (faster than GPT-5)

Avoid For

Custom GPT actions (broken post-update)

Scheduled tasks (execution issues)

Cases needing reliable tool integration

200,000 context window

100,000 max output tokens

Jan 1, 2024 knowledge cutoff

Reasoning supported

Parameters

While OpenAI documents a unified parameter set for the Chat Completions and Responses APIs, each model supports only a limited subset of model-specific parameters and values. This table lists the supported model-specific GPT-5.1 API parameters and allowed values.

Parameter	Description	Path	Supported Values
Model	Selects the model version for the request	model	gpt-5.1gpt-5.1-2025-04-14
Message roles	Defines the role of the message in the input	messages[].role	developersystemuserassistant
Reasoning effort	Controls the depth of internal reasoning used by the model	reasoning_effort	nonelowmediumhigh
Reasoning summary	Controls whether the model produces a concise or detailed reasoning summary	reasoning_summary	detailedconciseautonull
Max output tokens	Max output tokens the model may generate	max_completion_tokens	16 .. 100,000
Verbosity	Controls how brief or detailed the generated response is	verbosity	lowmediumhigh
Output format	Specifies the output format, including structured JSON schemas	response_format	textjson_objectjson_schema
Temperature	Controls how random or deterministic the output is	temperature	Not supported
Top P	Controls how diverse the output tokens are	top_p	Not supported
Presence penalty	Encourages the model to introduce new topics	presence_penalty	Not supported
Frequency penalty	Reduces repetition of the same words or phrases	frequency_penalty	Not supported

Pricing

GPT-5.1 API pricing is based on token usage for input and output. Prices are listed per 1M tokens, with lower rates for cached input. Tool-specific features may add per-call fees.

Text tokens

Per 1M tokens

Input$1.25

Cached input$0.13

Output$10.00

Example costs (GPT-5.1)

TASK

APPROX COST

Analyze 100-page PDF

~$0.01–$0.04

Long code review (10k lines of code)

~$0.02–$0.06

Research report (15k words)

~$0.02–$0.05

One verbose agent run (50k output tokens)

~$0.50

Modalities

What the model can accept and produce

TextInput and output

ImagesInput only

AudioNot supported

VideoNot supported

Features

Platform-level capabilities

StreamingSupported

Function callingSupported

Structured outputsSupported

Fine-tuningNot supported

DistillationSupported

Predicted outputsNot supported

Tools

Tools supported by this model when using the Responses API.

Web searchSupported

File searchSupported

Image generationSupported

Code interpreterSupported

MCPSupported

Computer useNot supported

Snapshots

GPT-5.1 model snapshots ensure stable behavior by locking a specific version. See all available snapshots and aliases below.

gpt-5.1

↪ gpt-5.1-2025-11-13

gpt-5.1-2025-11-13

FAQs

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