Model comparison - Same provider, successor
GPT-5.6 Luna vs GPT-6 Luna
GPT-5.6 Luna and GPT-6 Luna are both OpenAI models. On list price, GPT-5.6 Luna charges 2x GPT-6 Luna's input price ($0.20 vs $0.10 per 1M tokens), and GPT-5.6 Luna charges 2.4x GPT-6 Luna's output price ($1.20 vs $0.50 per 1M tokens). GPT-5.6 Luna and GPT-6 Luna both have a 1,050,000-token context window, and both return up to 128,000 output tokens per response. GPT-5.6 Luna was released on July 9, 2026 and GPT-6 Luna on September 22, 2026. Both are closed-weights models, available only through an API.
Last verified from each provider's pricing page. All sources
Side-by-side specs
| Spec | GPT-5.6 Luna | GPT-6 Luna |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Input / 1M tokens | $0.20 | $0.10 |
| Output / 1M tokens | $1.20 | $0.50 |
| Cache read / 1M | $0.02 | $0.01 |
| Cache write / 1M | $0.25 | $0.125 |
| Batch input / 1M | $0.10 | $0.05 |
| Batch output / 1M | $0.60 | $0.25 |
| Long-context rates above | 272,000 tokens | 272,000 tokens |
| Context window | 1,050,000 | 1,050,000 |
| Max output | 128,000 | 128,000 |
| Release date | ||
| Weights | Closed | Closed |
| API model id | gpt-5.6-luna | gpt-6-luna |
| AI Gateway id | openai/gpt-5.6-luna | openai/gpt-6-luna |
| Last verified |
Prices in USD per 1M tokens at each provider's standard first-party rate. A dash means the provider does not bill that item separately or no primary page states it.
What each costs in practice
The same three workloads every model page uses, worked from each model's standard list rates. Swap in your own token counts with the math on each model's page.
| Workload | GPT-5.6 Luna | GPT-6 Luna |
|---|---|---|
| One agent session1M input tokens and 100K output tokens, no caching. | $0.32 | $0.15 |
| A chat app10,000 requests a day at 2K input and 500 output tokens each. | $10.00$300.00 per 30-day month | $4.50$135.00 per 30-day month |
| The same session at a 90% cache hit90% of the input is read from the prompt cache. The one-time cache write premium is not included. | $0.158 | $0.069 |
Show the math
GPT-5.6 Luna
- One agent sessionInput: 1M x $0.20 = $0.20Output: 0.1M x $1.20 = $0.12
- A chat appInput: 20M x $0.20 = $4.00Output: 5M x $1.20 = $6.00
- The same session at a 90% cache hitCached input: 0.9M x $0.02 = $0.018Uncached input: 0.1M x $0.20 = $0.02Output: 0.1M x $1.20 = $0.12
GPT-6 Luna
- One agent sessionInput: 1M x $0.10 = $0.10Output: 0.1M x $0.50 = $0.05
- A chat appInput: 20M x $0.10 = $2.00Output: 5M x $0.50 = $2.50
- The same session at a 90% cache hitCached input: 0.9M x $0.01 = $0.009Uncached input: 0.1M x $0.10 = $0.01Output: 0.1M x $0.50 = $0.05
Benchmarks under the same setting
Only boards that list both models under the same run setting appear here, one row per board and setting, with each score exactly as the board shows it. Scores on different boards use different scales and are never combined.
| Board and setting | GPT-5.6 Luna | GPT-6 Luna |
|---|---|---|
| Terminal-Bench 4.0agent: Codex; effort: maxOfficial leaderboard - tbench.ai | 17.3% ± 2.8% | 16.4% ± 2.7% |
Set them up in your tools
Step-by-step guides whose official docs list GPT-5.6 Luna or GPT-6 Luna by model id.
Model pages
FAQ
How do GPT-5.6 Luna and GPT-6 Luna compare on price?
On list price, GPT-5.6 Luna charges 2x GPT-6 Luna's input price ($0.20 vs $0.10 per 1M tokens), and GPT-5.6 Luna charges 2.4x GPT-6 Luna's output price ($1.20 vs $0.50 per 1M tokens). For one agent session of 1M input and 100K output tokens with no caching, that is $0.32 on GPT-5.6 Luna and $0.15 on GPT-6 Luna. Prices are each provider's first-party list rates, verified October 17, 2026 and October 17, 2026.
What are the context windows of GPT-5.6 Luna and GPT-6 Luna?
GPT-5.6 Luna and GPT-6 Luna both have a 1,050,000-token context window, and both return up to 128,000 output tokens per response.
Are GPT-5.6 Luna and GPT-6 Luna open weights?
GPT-5.6 Luna is closed-weights and is called through OpenAI's API as gpt-5.6-luna. GPT-6 Luna is closed-weights and is called through OpenAI's API as gpt-6-luna.
More comparisons
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- DeepSeek V4.1 Flash vs GPT-6 LunaOpen weights vs closed
- GLM-5.3-Flash vs GPT-6 LunaSimilar price, same tier
- GPT-6 Luna vs Qwen3.8-FlashSimilar price, same tier
- GPT-6 Luna vs MiniMax-M3Open weights vs closed
- GPT-6 Luna vs Mistral Small 4Similar price, same tier
Sources
GPT-5.6 Luna verified from developers.openai.com; GPT-6 Luna verified from developers.openai.com. This page is as current as the older of the two: .
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