AI model comparison
GPT-6 Luna vs GPT-5.6 Luna Pro
Pricing, context window, benchmarks, and features compared side by side. Or skip the guesswork and send one prompt to both.
OpenAI
GPT-6 Luna
GPT-6 Luna is the fast, cost-efficient model in OpenAI's GPT-6 series, positioned below GPT-6 Sol.
- Input / 1M
- $0.10
- Output / 1M
- $0.50
- Context
- 1.05M
OpenAI
GPT-5.6 Luna Pro
GPT-5.6 Luna Pro is the same underlying model as [GPT-5.6 Luna](https://openrouter.ai/openai/gpt-5.6-luna), served with `reasoning.mode` set to `pro` for higher-quality responses on complex tasks.
- Input / 1M
- $0.20
- Output / 1M
- $1.20
- Context
- 1.05M
At a glance
Quick verdict
How the two models stack up on the things people ask about most.
Lower price
GPT-6 Luna
2.2x cheaper for a typical chat
Higher intelligence score
Tie
Not enough benchmark data
Larger context window
Tie
1.05M vs 1.05M tokens
Newer release
GPT-6 Luna
Released September 22, 2026
Benchmarks
Benchmark scores
Independent scores from Artificial Analysis. Higher is better.
Intelligence index
GPT-6 Luna38.1GPT-5.6 Luna ProNot availableCoding index
GPT-6 LunaNot availableGPT-5.6 Luna ProNot availableAgentic index
GPT-6 LunaNot availableGPT-5.6 Luna ProNot availablePricing
GPT-6 Luna vs GPT-5.6 Luna Pro API pricing
Per-token API rates. Cheaper option highlighted.
| Metric | GPT-6 Luna | GPT-5.6 Luna Pro |
|---|---|---|
| Input tokensPer 1M tokens | $0.10 | $0.20 |
| Output tokensPer 1M tokens | $0.50 | $1.20 |
| Cached input (read)Per 1M tokens | $0.01 | $0.02 |
| Cache writePer 1M tokens | $0.13 | $0.25 |
| Long-context pricingPer 1M tokens, for very long prompts | $0.20 in / $0.75 out above 272K | $0.40 in / $1.80 out above 272K |
| Web searchPer request | $0.01 | $0.01 |
What it costs in practice
Estimated cost per 1,000 requests at standard rates. Coding and long-document figures also show the cost when the input is already cached.
Chat message
2K in, 500 out
GPT-6 Luna$0.45GPT-5.6 Luna Pro$1Coding task
30K in, 4K out
GPT-6 Luna$5$2.30 cachedGPT-5.6 Luna Pro$10.80$5.40 cachedLong document summary
150K in, 2K out
GPT-6 Luna$16$2.50 cachedGPT-5.6 Luna Pro$32.40$5.40 cachedSpecs
Context window and capabilities
How much each model can read, how much it can write, and what it accepts as input.
| Metric | GPT-6 Luna | GPT-5.6 Luna Pro |
|---|---|---|
| Context window | 1.05M tokens | 1.05M tokens |
| Max output | 128K tokens | 128K tokens |
| Input types | File, Image, Text | File, Image, Text |
| Output types | Text | Text |
| Reasoning effort levels | Max, Extra high, High, Medium, Low, None | Max, Extra high, High, Medium, Low, None |
| Default reasoning effort | Medium | Medium |
| Release date | September 22, 2026 | July 9, 2026 |
Features
Supported features
API features available for each model.
| Metric | GPT-6 Luna | GPT-5.6 Luna Pro |
|---|---|---|
| Tool calling | Supported | Supported |
| Structured outputs | Supported | Supported |
| JSON mode | Supported | Supported |
| Reasoning | Supported | Supported |
| Temperature | Not supported | Not supported |
| Stop sequences | Not supported | Not supported |
| Deterministic seed | Supported | Supported |
| Verbosity control | Supported | Supported |
Keep exploring
More on these models
Other head-to-heads, the full model page, and the alternatives list for each model.
GPT-6 LunaView full model details- GPT-6 Luna vs DeepSeek V4.1 Flash
- GPT-6 Luna vs GLM 5.3 Flash
- GPT-6 Luna vs MiMo-V2.6-Flash
- GPT-6 Luna vs Hy4 preview
- GPT-6 Luna vs DeepSeek V4 Flash 0731
- GPT-6 Luna vs Claude Opus 5.5
- GPT-6 Luna vs GLM 5.3
- GPT-6 Luna vs DeepSeek V4 Flash 0423
- GPT-6 Luna vs Step 5 Preview
- GPT-6 Luna vs Gemini 3.8 Flash
- GPT-6 Luna vs Hy3
- GPT-6 Luna vs GPT-5.6 Luna
- GPT-6 Luna vs GPT-6.1 Sol
- GPT-6 Luna vs Muse Spark 1.3 Contributor
- GPT-6 Luna vs Claude Sonnet 5.5
- GPT-6 Luna vs MiMo-V2.6-Pro
- GPT-6 Luna vs DeepSeek V4 Pro 0813
- GPT-6 Luna vs GPT-6 Astra
- GPT-6 Luna vs Claude Opus 5
- GPT-6 Luna vs Claude Fable 5.1
- GPT-6 Luna vs DeepSeek V4 Pro 0423
- GPT-6 Luna vs Solar Pro 4
- GPT-6 Luna vs GPT-6 Luna Pro
- GPT-6 Luna vs Claude Haiku 5.5
- GPT-6 Luna vs Ling 3.1 Flash
- GPT-6 Luna vs Qwen3.8 Flash
- GPT-6 Luna vs Qwen3.7 Flash
- GPT-6 Luna vs DeepSeek V4 Flash Vision Exp
- GPT-6 Luna vs GLM 5.3 FlashX
GPT-5.6 Luna ProView full model details- GPT-5.6 Luna Pro vs DeepSeek V4.1 Flash
- GPT-5.6 Luna Pro vs GLM 5.3 Flash
- GPT-5.6 Luna Pro vs Hy4 preview
- GPT-5.6 Luna Pro vs DeepSeek V4 Flash 0731
- GPT-5.6 Luna Pro vs DeepSeek V4 Flash 0423
- GPT-5.6 Luna Pro vs GPT-5.6 Luna
- GPT-5.6 Luna Pro vs MiniMax M3
- GPT-5.6 Luna Pro vs GPT-5.4 Nano
- GPT-5.6 Luna Pro vs GPT-4.1 Mini
Our take
GPT-6 Luna is 2.2x cheaper for a typical chat. The right pick depends on your workload, so the quickest way to settle it is to send the same prompt to both and compare.
FAQ
Frequently asked questions
Is GPT-6 Luna or GPT-5.6 Luna Pro cheaper?
GPT-6 Luna is cheaper for a typical chat (2K input tokens and 500 output tokens). GPT-6 Luna costs $0.10 per 1M input tokens and $0.50 per 1M output tokens, while GPT-5.6 Luna Pro costs $0.20 per 1M input tokens and $1.20 per 1M output tokens.
Which has a bigger context window, GPT-6 Luna or GPT-5.6 Luna Pro?
GPT-6 Luna supports up to 1.05M tokens of context, compared with 1.05M for GPT-5.6 Luna Pro.
Can I use GPT-6 Luna and GPT-5.6 Luna Pro at the same time?
Yes. Shortcut Chat sends one prompt to multiple models at once, so you can see GPT-6 Luna and GPT-5.6 Luna Pro answer side by side and keep the better response.
Why choose? Ask both.
Send one prompt to GPT-6 Luna and GPT-5.6 Luna Pro at the same time. Compare the answers side by side and keep the best one.