---
title: "OpenAI: GPT-5.6 Luna — price, capability and what beats it · Undominated.ai"
canonical: https://undominated.ai/models/openai__gpt-5.6-luna/
description: "OpenAI: GPT-5.6 Luna: $0.200/M in, $1.20/M out. Independent capability scores, context-tier pricing, and the models that are both better and cheaper."
---

# OpenAI: GPT-5.6 Luna — price, capability and what beats it · Undominated.ai

> OpenAI: GPT-5.6 Luna: $0.200/M in, $1.20/M out. Independent capability scores, context-tier pricing, and the models that are both better and cheaper.

[Leaderboard](/) / OpenAI

# GPT-5.6 Luna

OpenAI · released 2026-07-09 · proprietary

 $0.450 per million tokens, balanced Balanced Summarise Chat Code gen Agentic

## Nothing is both better and cheaper.

Under a balanced workload, no other model in the catalogue scores higher *and* costs less. This model is on the value frontier.

The same model via **batch** is 50% cheaper ($0.225/M) — same weights, different latency.

## Our take

 editorial — not a measurement

The cheap end of the 5.6 family at $0.20/$1.20 with the full 1.05M context window, which is an unusually good context-per-dollar ratio for a proprietary model. It is also the model OpenAI gives away — ChatGPT Free offers unlimited Luna chat — which tells you where it sits on the capability curve. Treat it as a high-volume utility model: cheap, long-context, not frontier. The long-context tier doubles it to $0.40/$1.80, still cheap.

### Strengths

 - $0.20/$1.20 with a 1.05M context window
- Cached input at $0.02
- Cheapest route to a very long proprietary context
- 50% batch discount

### Weaknesses

 - Well below frontier capability — it is the free-tier ChatGPT model
- Long-context tier doubles input price
- Open-weight models undercut it on raw token price

### Reach for it when

 - High-volume summarisation over long documents
- Cheap long-context retrieval
- Free-tier-equivalent workloads at API scale

### Avoid it if

 - The task needs frontier reasoning
- You can host open weights

Sources: developers.openai.com · chatgpt.com

### Every price dimension

| Input | $0.200 /M |
| --- | --- |
| Output | $1.20 /M |
| Cached input | $0.020 /M |
| Cache write | $0.250 /M |
| Web search | $0.01 /call |
| Batch discount | 50% |

**Past 272,000 tokens the price changes.** Input goes to $0.400/M (2×) and output to $1.80/M. The headline rate does not apply to a long-context workload.

### Independent scores

| Intelligence | 52.3 |
| --- | --- |
| Coding | 71.4 |
| Agentic | 46.9 |
| LMArena Elo | 1428.5 xhigh |

Sources are listed separately rather than averaged. Across the 62 models both have scored they correlate at r = 0.806 — close agreement overall, but four models rank very differently between them, and a blended score would hide exactly those.

### Capability

| Context window | 1.1M |
| --- | --- |
| Max output | 128K |
| Input modes | file, image, text |
| Tool use | yes |
| Reasoning | optional |
| Knowledge cutoff | 2026-02-16 |
| Open weights | no |

### Provenance

| Price source | openrouter.ai |
| --- | --- |
| Fetched | 2026-08-24 |
| Quality data | verified |
| Cross-checked | vendor page |

GPT-5.6 Luna is a fast, cost-efficient model in OpenAI's GPT-5.6 series. It is suited for high-volume, latency-sensitive tasks such as chat, classification, and lightweight agentic workflows, providing capable reasoning for...