GPT-5.6 Luna Pro overview
GPT-5.6 Luna Pro by OpenAI
GPT-5.6 Luna Pro API runs through a chat completions endpoint, the same model as GPT-5.6 Luna with reasoning mode set to pro, trading speed for deeper reasoning on harder requests. 1,050,000-token context, 128,000-token output limit, function calling, structured outputs, image input.
GPT-5.6 Luna Pro specs
- Model ID
openai/gpt-5.6-luna-pro- Developer
- OpenAI
- Context window
- 1,050,000 tokens
- Max output
- 128,000 tokens
- Input
- Image, Text
- Output
- Text
- API
- OpenAI-compatible, base URL
https://api.aimlapi.com/v1
What Is GPT-5.6 Luna Pro API?
GPT-5.6 Luna Pro is described as the same underlying model as GPT-5.6 Luna, served with reasoning mode set to pro for higher-quality responses on complex tasks. It is listed as an OpenAI model under the id openai/gpt-5.6-luna-pro.
OpenAI’s documentation describes Luna as the cost-sensitive, high-volume GPT-5.6 tier, and separate guidance says pro mode performs more model work before returning a single final answer.
Technical Reference
| Developer | Open AI |
|---|---|
| Model ID | openai/gpt-5.6-luna-pro |
| Release Date | July 8, 2026 |
| Context Window | 1,050,000 tokens (~1.1M) |
| Max Output Tokens | 128,000 tokens |
| Modalities | Image, Text → Text |
| Capabilities | file input, parallel tool calls, reasoning, streaming, structured (JSON schema) output, tool/function calling, vision |
What GPT-5.6 Luna Pro Brings to the Table
Pro reasoning mode
The model uses reasoning.mode set to pro for higher-quality responses on complex tasks.
Underlying model
It is the same underlying model as GPT-5.6 Luna.
OpenAI API listing
OpenAI’s API documentation includes GPT-5.6 Luna as a named model, and third-party model listings identify the Pro variant by the exact id openai/gpt-5.6-luna-pro.
Higher-quality complex-task behavior
The pro configuration is described as doing more model work for difficult tasks before producing its final answer.
Where GPT-5.6 Luna Pro Makes the Most Sense
Complex task handling
Suitable for requests where additional model work is preferred to improve answer quality on harder problems.
High-volume workloads
The Luna tier is described as cost-sensitive and high-volume, making the Pro configuration relevant when that tier is needed with pro reasoning.
Single final-answer workflows
OpenAI’s pro mode guidance describes returning one final answer after additional internal work.
GPT-5.6 Luna Pro vs the Alternatives
GPT-5.6 Luna
The base Luna model is the same underlying model without the pro reasoning mode.
GPT-5.6 Terra
OpenAI positions Terra as a separate GPT-5.6 tier alongside Luna.
GPT-5.6 Sol
OpenAI positions Sol as another GPT-5.6 tier alongside Luna and Terra.
Sources: https://medium.com/@techlatest.net/gpt-5-6-models-explained-sol-vs-terra-vs-luna-pro-models-features-which-one-should-you-choose-6693668917f7 · https://openai.com/index/gpt-5-6/ · https://developers.openai.com/api/docs/models/gpt-5.6-luna
Use cases
GPT-5.6 Luna Pro is documented as suited for high-volume API workloads like summarization, classification, and data extraction. It is also suited for long-context document Q&A and legal or medical record analysis. Another documented use case is vision-enabled agents that parse screenshots, charts, and PDFs. It is also described as useful for coding assistance and multi-file repository reasoning.
Capabilities
- File input
- Reasoning
- Streaming
- Vision
GPT-5.6 Luna Pro API pricing
| Usage | Price | Unit |
|---|---|---|
| Input | $0.2116 | 1M tokens |
| Output | $1.27 | 1M tokens |
| Cached input | $0.0212 | 1M tokens |
Prices from the AI/ML API price list, checked on Nov 4, 2026.
GPT-5.6 Luna Pro vs other models: token prices
AI/ML API input and output rates for 5 models, per million tokens.
| Model | Input | Output |
|---|---|---|
 GPT-5.6 Luna Pro | $0.2116 | $1.27 |
| GPT-6 Luna | $0.1 | $0.5 |
| GPT-6.1 Terra | $1 | $5 |
| GPT-6.1 Sol | $2 | $10 |
| GPT-6.1 Terra Pro | $2.12 | $10.58 |
How to use the GPT-5.6 Luna Pro API
View docs
Build with your agent
Give your agent the model details, code and documentation.
1Get your API key
Create API keyexport AIMLAPI_KEY="8f2b4c7d9a1e6b3f…"2Make your first request
curl 'https://api.aimlapi.com/v1/chat/completions' \
-H "Authorization: Bearer $AIMLAPI_KEY" \
-H 'Content-Type: application/json' \
-d '{
"model": "openai/gpt-5.6-luna-pro",
"messages": [
{
"role": "user",
"content": "Write a haiku about the ocean."
}
]
}'import os
import requests
headers = {
"Authorization": f"Bearer {os.environ['AIMLAPI_KEY']}",
"Content-Type": "application/json",
}
payload = {
"model": "openai/gpt-5.6-luna-pro",
"messages": [
{
"role": "user",
"content": "Write a haiku about the ocean."
}
]
}
response = requests.post("https://api.aimlapi.com/v1/chat/completions", headers=headers, json=payload, timeout=120)
response.raise_for_status()
print(response.json())const response = await fetch("https://api.aimlapi.com/v1/chat/completions", {
method: "POST",
headers: {
Authorization: `Bearer ${process.env.AIMLAPI_KEY}`,
"Content-Type": "application/json",
},
body: JSON.stringify({
"model": "openai/gpt-5.6-luna-pro",
"messages": [
{
"role": "user",
"content": "Write a haiku about the ocean."
}
]
}),
});
if (!response.ok) throw new Error(`HTTP ${response.status}`);
console.log(await response.json());Models similar to GPT-5.6 Luna Pro
GPT-5.6 Luna Pro FAQ
What is the context window of GPT-5.6 Luna Pro?
GPT-5.6 Luna Pro has a 1,050,000 tokens context window and can return up to 128,000 tokens.
What inputs and outputs does GPT-5.6 Luna Pro support?
GPT-5.6 Luna Pro takes image, text as input and returns text.
What is the model ID for GPT-5.6 Luna Pro?
Use openai/gpt-5.6-luna-pro as the model id. Requests go to https://api.aimlapi.com/v1/chat/completions.
When was GPT-5.6 Luna Pro released?
GPT-5.6 Luna Pro became available on July 9, 2026.
How much does GPT-5.6 Luna Pro cost?
GPT-5.6 Luna Pro costs $0.2116 input and $1.27 output per 1M tokens on AI/ML API, billed as you go with no subscription.
Does GPT-5.6 Luna Pro support streaming?
Yes, GPT-5.6 Luna Pro can stream responses as they are generated.
Can GPT-5.6 Luna Pro read images?
Yes, GPT-5.6 Luna Pro accepts image input alongside text.
Who created GPT-5.6 Luna Pro?
GPT-5.6 Luna Pro was built by OpenAI.
Does GPT-5.6 Luna Pro support function calling or tool use?
Yes, it supports tools including parallel tool calls.