GPT-6 Luna
gpt-6-lunaOpenAI's most efficient model for focused, high-volume tasks. Reasoning, text and image input, function calling and tool use, 1,050,000-token context window and up to 128,000 output tokens. Knowledge cutoff May 18, 2026.
- Price · 1M in / out
- US$0.12 / US$0.60
- Context
- 1.050.000 tokens
- Max. output
- 128.000 tokens
- Input → output
- Text → Text
- Developer
- OpenAI
- Updated
- September 24, 2026
Playground
Try GPT-6 Luna
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This run
at most US$0.0007 · 0.07 credits reserved
Billed by the tokens actually used; the unused part of the reservation is refunded.
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10 free credits (US$0.10) when you sign up with Google
Usable 24 hours after sign-up, up to 5 runs per day and at most 2 credits per run. Other sign-in methods start without credits. Enough for 142 runs of this model.
About GPT-6 Luna
GPT-6 Luna is a model by OpenAI in the Text & chat category. On Railwail, GPT-6 Luna costs US$0.12 per 1M input tokens and US$0.60 per 1M output tokens. The context window holds 1.050.000 tokens, and one response can be up to 128.000 tokens long.
Pricing
| Input | US$0.12 / 1M tokens |
|---|---|
| Output | US$0.60 / 1M tokens |
| Input (prompts over 272.000 tokens) | US$0.24 / 1M tokens |
| Output (prompts over 272.000 tokens) | US$0.90 / 1M tokens |
- Billed by the tokens each request actually uses.
- 1 credit = US$0.01
Cost calculator
Price calculator
Total
US$0.05
5 credits
Per request
US$0.0005 · 0.05 credits
Each request is rounded up to 0.01 credits.
API
curl https://railwail.com/api/v1/chat/completions \
-H "Authorization: Bearer $RAILWAIL_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"model": "gpt-6-luna",
"messages": [
{
"role": "user",
"content": "Explain what a vector database is in two sentences."
}
],
"max_tokens": 1024
}'import os
from openai import OpenAI
client = OpenAI(
api_key=os.environ["RAILWAIL_API_KEY"],
base_url="https://railwail.com/api/v1",
)
completion = client.chat.completions.create(
model="gpt-6-luna",
messages=[
{
"role": "user",
"content": "Explain what a vector database is in two sentences.",
},
],
max_tokens=1024,
)
print(completion.choices[0].message.content)import OpenAI from "openai";
const client = new OpenAI({
apiKey: process.env.RAILWAIL_API_KEY,
baseURL: "https://railwail.com/api/v1",
});
const completion = await client.chat.completions.create({
model: "gpt-6-luna",
messages: [
{
role: "user",
content: "Explain what a vector database is in two sentences."
}
],
max_tokens: 1024
});
console.log(completion.choices[0].message.content);// npm install railwail
import railwail from "railwail";
const rw = railwail(process.env.RAILWAIL_API_KEY);
const res = await rw.chat("gpt-6-luna", [
{ role: "user", content: "Explain what a vector database is in two sentences." },
], { max_tokens: 1024 });
console.log(res.choices[0].message.content);Specifications
- Model ID
gpt-6-luna- Developer
- OpenAI
- Category
- Text & chat
- Input
- Text
- Output
- Text
- Context window
- 1.050.000 tokens
- Max. output
- 128.000 tokens
- Billing
- By usage (tokens or GPU time)
- Catalog entry updated
- September 24, 2026
Tags
- openai
- gpt-6
- cost-efficient
- fast
- reasoning
- vision
- tools
Use cases
Frequently asked questions
What is GPT-6 Luna?
GPT-6 Luna is a model by OpenAI in the Text & chat category. On Railwail you can call it with an API key through the Railwail API.
How much does GPT-6 Luna cost on Railwail?
On Railwail, GPT-6 Luna costs US$0.12 per 1M input tokens and US$0.60 per 1M output tokens. You are charged for what each request actually uses. Usage is paid from prepaid credits; 1 credit equals US$0.01.
What is the context window of GPT-6 Luna?
The context window of GPT-6 Luna holds 1.050.000 tokens. One response can be up to 128.000 tokens long.
How fast is GPT-6 Luna?
There are not enough measured runs of GPT-6 Luna on Railwail yet to state a run time. It depends on the input, the settings and the load at the provider.
Is GPT-6 Luna better than Claude Fable 5.1?
That depends on the task. GPT-6 Luna (OpenAI) and Claude Fable 5.1 (Anthropic) are both models in the Text & chat category. The comparison page shows their prices and specifications side by side.
Compare GPT-6 Luna and Claude Fable 5.1How do I use GPT-6 Luna through the API?
Create a Railwail API key and send your request with the model ID gpt-6-luna. Code examples for curl, Python and JavaScript are in the API section of this page.
Comparable models
All in this category- Claude Fable 5.1Anthropic
Anthropic's model for the most demanding reasoning and long-horizon agentic work. 1M-token context window, up to 128K output tokens, adaptive thinking that is always on.
- Claude Opus 4.8Anthropic
The most capable model of Anthropic's Opus 4 series. State of the art on long-horizon agentic work, coding and knowledge tasks, with a 1M-token context window at standard pricing.
- Claude Opus 5.5Anthropic
Anthropic's current Opus model for long-running agentic coding and knowledge work. 1M-token context window, up to 128K output tokens, adaptive thinking that is always on.
Use GPT-6 Luna via the API
One API key for every model on Railwail. Usage is charged from prepaid credits, 1 credit = US$0.01.