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Cheap GPT-5.6 Luna API
GPT-5.6 Luna is OpenAI's ChatGPT model listed at $1 / $6 per 1M input/output tokens. Through Somnus every top-up is credited at 2× to 2.5×, so you effectively pay $0.5 / $3 or less, on the same OpenAI-compatible key as 50+ other models.
What a top-up buys on GPT-5.6 Luna
| You pay | Credit | ≈ 1M output tokens of GPT-5.6 Luna |
|---|---|---|
| $20 (2×) | $40 | 6.7 |
| $50 (2.2×) | $110 | 18 |
| $100 (2.35×) | $235 | 39 |
| $200 (2.5×) | $500 | 83 |
Output-token count only; input tokens are cheaper. First top-up is at least 2.5×.
When to pick GPT-5.6 Luna
GPT-5.6 Luna costs $0.0045 per 1,500-in/500-out request at list price, $0.0022 effective. It sits in the mid price range — a good default for production apps.
GPT-5.6 Luna vs similarly priced models
| Model | Maker | List (in / out) | Effective | Same request, effective |
|---|---|---|---|---|
| GLM 5.3 | Zhipu | $1.4 / $4.4 | $0.7 / $2.2 | $0.0022 |
| Qwen 3.8 Max | Alibaba | $1.65 / $4.95 | $0.83 / $2.48 | $0.0025 |
| Claude Haiku 4.5 | Anthropic | $1 / $5 | $0.5 / $2.5 | $0.0020 |
| Gemini 3.8 Flash | $0.75 / $3.75 | $0.38 / $1.88 | $0.0015 |
Nearest models to GPT-5.6 Luna by blended price (3 input : 1 output). All run on one Somnus key.
Getting the most out of GPT-5.6 Luna for less
- Input is 6.0× cheaper than output on GPT-5.6 Luna, so long context with short answers is the cheapest pattern.
- A $200 top-up gives $500 credit — about 222M blended GPT-5.6 Luna tokens.
- Mix models: send easy steps to DeepSeek V4 Flash and keep GPT-5.6 Luna for the steps that need it.
Other ChatGPT models on Somnus
| Model | List (in / out) | Effective | vs GPT-5.6 Luna |
|---|---|---|---|
| GPT-6 Astra | $10 / $50 | $5 / $25 | 8.89× the price |
| GPT-5.6 Sol | $5 / $30 | $2.5 / $15 | 5.00× the price |
Every OpenAI model shares the same key and balance.
Use GPT-5.6 Luna
import OpenAI from "openai";
const client = new OpenAI({
apiKey: process.env.SOMNUS_API_KEY,
baseURL: "https://gateway-production-c837.up.railway.app/v1",
});
const resp = await client.chat.completions.create({
model: "claude-sonnet-5",
messages: [
{"role": "user", "content": "Summarise this in one line"}
],
});
console.log(resp.choices[0].message.content);Copy the exact model id from your dashboard.
Questions
Is GPT-5.6 Luna really cheaper on Somnus?
Usage is billed at OpenAI's list price, but each dollar you pay is credited as $2–$2.50, so the effective price is half or less.
Do I need a subscription?
No. Top up any amount from $5, or start with the free $5 credit.
Is Somnus affiliated with OpenAI?
No. Somnus is an independent gateway.
Try GPT-5.6 Luna with free credit
$5 free on sign-up, then 2× or more on every top-up.
Create a free accountRelated
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