GPT-5.6 Luna Pro
by OpenAI · openai/gpt-5.6-luna-pro · #150 cheapest of 422 paid models
Prices updated Sep 19, 2026, 6:22 PM UTC · refreshed hourly
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. Learn more in OpenAI's docs: https://developers.openai.com/api/docs/guides/reasoning#reasoning-mode
Compare vs:Claude Sonnet 5Claude Opus 4.6Claude Haiku 4.5Gemini 3.6 Flash
Pricing
Input
$0.20
per 1M tokens
Output
$1.20
per 1M tokens
Blended (3:1)
$0.45
3 input : 1 output
Cache read
$0.02
per 1M cached tokens
Cache write
$0.25
per 1M tokens
Cache & batch economics
Effective prices for GPT-5.6 Luna Pro with prompt caching.
| Cache hit rate | Effective blended $/1M | Example request* | vs no cache |
|---|---|---|---|
| 0% | $0.45 | $0.0216 | — |
| 50% | $0.382 | $0.0126 | −42% |
| 90% | $0.328 | $0.0054 | −75% |
*Example: 100K sticky context + 2K new input + 1K output. Batch discount is an approximate 50% off list rates for this provider’s batch API. Confirm on the vendor’s pricing page.
What a request costs
| Workload | Input tokens | Output tokens | Cost / request | Cost / 1K requests |
|---|---|---|---|---|
| Short chat message | 500 | 300 | $0.00046 | $0.46 |
| Document summary | 8,000 | 1,000 | $0.0028 | $2.80 |
| Codebase question (RAG) | 30,000 | 2,000 | $0.0084 | $8.40 |
| Long-context analysis | 150,000 | 5,000 | $0.036 | $36.00 |
Specs
Context window
1.05M
tokens
Max output
128K
tokens
Input modalities
file, image, text
Tokenizer
GPT