gpt 5.1 chat Adaptive Reasoning
gpt 5.1 chat carries the ChatGPT-tuned reasoning that improves accuracy on technical and math prompts over GPT-5.0. Need configurable reasoning_effort? Use the full gpt-5.1 model instead.
GPT 5.1 Chat Latest
The gpt-5.1 chat latest API serves the GPT-5.1 snapshot that ran inside ChatGPT, tuned for fast, natural conversation. With a 128K-token context window, text and image input, and native function calling, gpt 5.1 chat fits chatbots, support agents, and RAG. Generate one GPTProto gpt 5.1 chat api key and call it alongside gpt 5.5 and every other model from a single endpoint.
API Usage Examples
curl --request POST "https://gptproto.com/v1/chat/completions" \
--header "Authorization: Bearer $GPTPROTO_API_KEY" \
--header "Content-Type: application/json" \
--data '{
"model": "gpt-5.1-chat-latest",
"messages": [
{
"role": "user",
"content": "Hello"
}
]
}'GPT 5.1 Chat Latest pricing
Estimate a request with real work scenarios. GPTProto token pricing is 20% below official rates.
Cost calculator
Multi-turn agent with cached context.
$1 / 1M$0.0015
$8 / 1M$0.0064
$0.1 / 1M$0.0003
$0.1 / 1M$0.0025
Cost per request$0.0107
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gpt-5.1 chat latest API
Verified specs, pricing, and how gpt 5.1 chat compares to gpt 5.1 and gpt 5.5 — one GPTProto key for all of them.
Agentic Tool Use
The gpt-5.1 chat latest API supports native function calling and structured JSON outputs, so your agents trigger tools and return clean, parseable results across multi-step workflows — no extra glue layer required.
128K Context Window
gpt 5.1 chat handles a 128K-token context window with up to 16K output tokens — enough for long conversations, document Q&A, and retrieval pipelines without mid-thread truncation.
Text + Image Vision
The gpt 5.1 chat api accepts text and image input in a single call for screenshot reading, chart parsing, and visual Q&A. Note: this model does not process video or audio.
Related Models
All Models| Model | Input → Output | ||||
|---|---|---|---|---|---|
 | — | $1.00 / $8.00 per 1M | $0.10 / $0.10 per 1M | Input: TextInput: ImageInput: Document Output: Text | |
| 500K | $1.20 / $3.60 per 1M | — / $0.30 per 1M | Input: TextInput: Image Output: Text | ||
| 1M | $1.80 / $5.40 per 1M | $2.25 / $0.23 per 1M | Input: TextInput: ImageInput: VideoInput: Document Output: Text | ||
| 1M | $4.00 / $20.00 per 1M | $5.00 / $0.40 per 1M | Input: TextInput: ImageInput: Document Output: Text | ||
| 1.05M | $0.90 / $4.50 per 1M | $0.09 / $0.09 per 1M | Input: TextInput: ImageInput: Document Output: Text | ||
| 1.05M | $0.18 / $1.50 per 1M | $0.02 / $0.02 per 1M | Input: TextInput: ImageInput: Document Output: Text | ||
| 1.05M | $2.70 / $13.50 per 1M | $0.27 / $0.27 per 1M | Input: TextInput: ImageInput: Document Output: Text | ||
| 1.05M | $0.16 / $0.96 per 1M | $0.20 / $0.02 per 1M | Input: TextInput: ImageInput: Document Output: Text | ||
| 1.05M | $1.60 / $9.60 per 1M | $2.00 / $0.16 per 1M | Input: TextInput: ImageInput: Document Output: Text | ||
| 1.05M | $4.00 / $24.00 per 1M | $5.00 / $0.40 per 1M | Input: TextInput: ImageInput: Document Output: Text | ||
| 500K | $1.20 / $3.60 per 1M | $0.30 / $0.30 per 1M | Input: TextInput: Image Output: Text | ||
| 1M | $1.60 / $8.00 per 1M | $2.00 / $0.16 per 1M | Input: TextInput: Document Output: Text | ||
| 1.05M | $0.48 / $0.96 per 1M | $0.10 / $0.10 per 1M | Input: TextInput: ImageInput: Document Output: Text | ||
| 1.05M | $1.26 / $3.96 per 1M | $0.23 / $0.23 per 1M | Input: TextInput: ImageInput: Document Output: Text | ||
| 1M | $8.00 / $40.00 per 1M | $10.00 / $0.80 per 1M | Input: TextInput: Document Output: Text | ||
| 1M | $0.36 / $1.44 per 1M | $0.07 / $0.07 per 1M | Input: TextInput: Document Output: Text | ||
| 1.05M | $0.90 / $5.40 per 1M | $0.09 / $0.09 per 1M | Input: TextInput: ImageInput: Document Output: Text | ||
| — | 1.05M | $0.14 / $0.28 per 1M | — / $0.0028 per 1M | Input: Text Output: Text | |
| 1.05M | $1.04 / $2.09 per 1M | $0.0087 / $0.0087 per 1M | Input: Text Output: Text | ||
| 1M | $0.75 / $1.50 per 1M | $0.12 / $0.12 per 1M | Input: TextInput: Image Output: Text | ||
| 1.05M | $24.00 / $144.00 per 1M | — | Input: TextInput: ImageInput: Document Output: Text | ||
| 1.05M | $24.00 / $144.00 per 1M | — | Input: TextInput: ImageInput: Document Output: Text | ||
| 1.05M | $4.00 / $24.00 per 1M | $0.40 / $0.40 per 1M | Input: TextInput: ImageInput: Document Output: Text | ||
| 262K | $0.85 / $3.60 per 1M | $0.14 / $0.14 per 1M | Input: TextInput: Document Output: Text | ||
| 205K | $1.26 / $3.96 per 1M | $0.23 / $0.23 per 1M | Input: TextInput: Document Output: Text | ||
| 203K | $1.08 / $3.60 per 1M | $0.22 / $0.22 per 1M | Input: TextInput: Document Output: Text | ||
| 164K | $0.17 / $0.25 per 1M | $0.02 / $0.02 per 1M | Input: Text Output: Text | ||
| 205K | $0.24 / $0.96 per 1M | $0.30 / $0.02 per 1M | Input: TextInput: Document Output: Text | ||
| 262K | $0.54 / $2.70 per 1M | $0.09 / $0.09 per 1M | Input: TextInput: Document Output: Text | ||
| — | $0.04 / $0.18 per 1M | $0.009 / $0.009 per 1M | Input: Text Output: Text | ||
| 262K | $0.10 / $0.97 per 1M | — | Input: TextInput: Image Output: Text | ||
| 262K | $0.10 / $0.97 per 1M | — | Input: TextInput: Image Output: Text | ||
| 262K | $0.02 / $0.18 per 1M | — | Input: TextInput: Image Output: Text |
What Is the gpt-5.1 chat latest API?
The gpt-5.1 chat latest API exposes the exact GPT-5.1 snapshot that powered ChatGPT, delivered through GPTProto's unified endpoint. Unlike the full gpt-5.1 reasoning model, the chat-latest alias is tuned for fast, conversational replies — a 128K context window, text-and-image input, streaming, and native function calling — which makes it a drop-in pick for chatbots, support flows, and lightweight RAG. One key reaches gpt 5.1 chat and every other model on the platform.
GPT-5.1 Chat latest vs GPT 5.1 vs GPT 5.5
| gpt-5.1 chat latest | gpt 5.1 | gpt 5.5 | |
|---|---|---|---|
| Best for | Chat, support bots, light RAG | Agentic + coding, reasoning | Frontier reasoning, long-doc |
| Context window | 128K | 400K | 1M |
| Max output | 16K | 128K | 128K |
| Reasoning control | Chat-tuned (fixed) | reasoning_effort none–high |
reasoning_effort none–xhigh |
| Input | Text + image | Text + image | Text + image |
| Video / audio | ✗ / ✗ | ✗ / ✗ | ✗ / ✗ |
| Knowledge cutoff | Sep 30 2024 | Sep 30 2024 | Dec 1 2025 |
| Price (OpenAI list) | $1.25 / $10 | $1.25 / $10 | $5 / $30 |
| Price on GPTProto | $1 / $8 | $0.875 / $7 | $4 / $24 |
| Status | Deprecated snapshot | Current | Current flagship |
gpt 5.1 chat latest vs gpt 5.1
The difference is snapshot vs base model. The full gpt-5.1 model ships a 400K context window and configurable reasoning_effort (none, low, medium, high) for agentic and coding work. The gpt-5.1 chat latest alias mirrors the ChatGPT chat experience: lower latency, a 128K window, and conversational tuning rather than long step-by-step reasoning. Choose the chat alias for dialogue; choose gpt 5.1 for tool-heavy autonomous tasks.
gpt-5.1 chat latest vs gpt 5.5
gpt 5.5 is OpenAI's current flagship — a 1M-token context window and stronger reasoning at a higher price. gpt 5.1 chat is cheaper and faster for everyday chat, but for long-document analysis or frontier accuracy, gpt 5.5 is the upgrade — available under the same GPTProto key, so migrating is a one-line model swap.
Is ChatGPT 5.1 being retired? Is it better than GPT-5.0?
Yes — OpenAI retired the GPT-5.1 family from ChatGPT on March 11, 2026, migrating conversations to newer 5.x models, and the gpt-5.1-chat-latest API snapshot is now marked deprecated. It stays reachable through GPTProto for teams that pinned to it. Versus GPT-5.0, gpt 5.1 chat brought a warmer tone and more reliable instruction-following; against the 5.5 line it now trails on context length and reasoning. Starting fresh? Build on gpt 5.5 and keep gpt 5.1 chat for parity testing or legacy compatibility.
At GPTProto, gpt-5.1 chat latest API pricing runs $1 / $8 per 1M input/output tokens — under OpenAI's $1.25 / $10 list — with one key spanning every model on the platform.
gpt 5.1 chat Frequently Asked Questions
Expert answers to common technical queries about gpt 5.1 chat integration and reasoning capabilities.
How does gpt 5.1 chat handle System 2 reasoning?
The gpt 5.1 chat model uses a native reasoning engine to verify its logic before outputting text. This process, controlled by the reasoning_effort parameter, allows the gpt to pause and 'think' through multi-step problems in math, physics, and code, resulting in 40% fewer logical fallacies compared to older gpt versions like 4o.
What is the context window for gpt 5.1 chat?
gpt 5.1 chat has a 128K-token context window with up to 16K output tokens — enough for long conversations, document Q&A, and RAG context in a single request. Cached input tokens are billed at a lower rate, so repeated system prompts stay cost-efficient across gpt 5.1 chat sessions. For 400K or 1M-token jobs, step up to gpt-5.1 or gpt 5.5.
Can gpt 5.1 chat process video files directly?
No. gpt 5.1 chat accepts text and image input only — video and audio are not supported on this model. You can pass screenshots, charts, and photos for visual Q&A, but for video you'll need to extract frames as images first, or use a dedicated video model on the platform.
How do I configure gpt 5.1 chat reasoning_effort?
The reasoning_effort parameter (none, low, medium, high) is configured on the gpt-5.1 model, not the chat-latest alias, which is tuned for fast conversation. To dial reasoning depth for coding or math, call gpt-5.1 and set reasoning_effort in your request; stay on gpt 5.1 chat when low-latency dialogue matters more than deep reasoning.
Is gpt 5.1 chat suitable for real-time voice apps?
While gpt 5.1 chat supports audio, its reasoning overhead creates latency that may exceed the sub-200ms requirements for fluid voice-to-voice bots. For those use cases, we recommend gpt 4o-Realtime, as gpt 5.1 chat is optimized for depth and accuracy rather than raw conversational speed.
Is my data used to train the gpt 5.1 chat model?
No. When using gpt 5.1 chat via GPTProto, your data is protected. Our platform and the underlying OpenAI API agreement strictly prohibit the use of customer inputs or outputs for training gpt foundation models, ensuring enterprise-grade privacy for all your gpt 5.1 chat projects.