# OpenAI GPT-5.6 Luna API

> GPT-5.6 Luna is the smallest, fastest tier of OpenAI's GPT-5.6 reasoning family, with text and image input; OpenAI says it roughly corresponds to the nano tier of earlier GPT-5 families. It is designed for high-volume workloads such as classification, extraction, routing, chat and lightweight agent steps where throughput and latency matter. Pick GPT-5.6 Terra or GPT-5.6 Sol when tasks need more capability, and the pro variant when a hard request needs more reasoning work.

Source: https://www.sandbase.ai/models/openai/gpt-5.6-luna
API reference: https://www.sandbase.ai/models/openai/gpt-5.6-luna/docs

## Facts

- Provider: OpenAI
- Type: Language model
- Model ID: `openai/gpt-5.6-luna`
- Price: $0.18 per 1M input tokens, $1.08 per 1M output tokens (10% off list price)
- Context window: 1.1M tokens, up to 128K output tokens
- Capabilities: chat, vision, reasoning, structured output, function calling
- Billing: pay per use from one SandBase balance; no provider account or subscription needed

## Call it

- Responses API: `POST https://api.sandbase.ai/v1/responses`
- Chat Completions API: `POST https://api.sandbase.ai/v1/chat/completions`

```bash
curl -X POST https://api.sandbase.ai/v1/responses \
  -H "Authorization: Bearer $SANDBASE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "model": "openai/gpt-5.6-luna",
  "input": "Hello",
  "max_output_tokens": 2048
}'
```

## FAQ

### How do I call OpenAI GPT-5.6 Luna through SandBase?

Create a SandBase API key, then send requests with the model ID "openai/gpt-5.6-luna" to Responses API (/v1/responses) or Chat Completions API (/v1/chat/completions) at https://api.sandbase.ai. The request examples on this page show the exact payload.

### How much does OpenAI GPT-5.6 Luna cost?

$0.18 per 1M input tokens and $1.08 per 1M output tokens with the current 10% discount (list price $0.20 / $1.20), billed per request from your SandBase balance.

### What is the context window of OpenAI GPT-5.6 Luna?

1.1M tokens of context, with up to 128K output tokens per response.

### How does OpenAI GPT-5.6 Luna score on benchmarks?

OpenAI GPT-5.6 Luna scores 37.3 on the Artificial Analysis Intelligence Index (v4.3), ranking #30 of 83 models on SandBase; Coding Index 71.4, Agentic Index 42.1. Source: Artificial Analysis, measured as GPT-5.6 Luna (Max).

### Which features does OpenAI GPT-5.6 Luna support?

OpenAI GPT-5.6 Luna supports vision (image input), reasoning, function calling, structured output. See Specifications above for the full list.

### Do I need a separate OpenAI account?

No. One SandBase API key and balance gives you access to OpenAI GPT-5.6 Luna and the other models in the catalog; you do not need to sign up with OpenAI separately.