GPT-5.6 Sol
Knows up to February 2026Missing 1,919 events
gpt-5.6-sol
$4 in, $20 out per 1M tokens
GPT-5.6 Luna
Low-cost high-volume tasks.
Model idgpt-5.6-luna
Price$0.20 in, $1.20 out per 1M tokens
Checked29 September 2026
Knows up to February 2026
1,919events after its cutoff
85 historic, 439 major. 258 days of news.
It launched on 9 July 2026, already missing 138 of them.
How to call it
4 ways to use GPT-5.6 Luna, with the model id each provider expects.
| Provider | Model id | Endpoint | Docs |
|---|---|---|---|
| OpenAI API | gpt-5.6-luna |
https://api.openai.com/v1/responses |
developers.openai.com |
| Azure OpenAI (Microsoft Foundry) | gpt-5.6-luna |
learn.microsoft.com | |
| OpenRouter | openai/gpt-5.6-luna |
openrouter.ai | |
| Web app | chatgpt.com |
Pricing
| Input | $0.20 per 1M tokens |
|---|---|
| Cached input | $0.02 per 1M tokens |
| Output | $1.20 per 1M tokens |
As published: “per 1M tokens (USD), standard tier”. Note: prompts >272K input tokens billed 2x input / 1.5x output.
Source: developers.openai.com, checked 29 September 2026.
Specs
- Input
- Text and images
- Output
- Text
- Context window
- 1,050,000 tokens
- Max output
- 128,000 tokens
- Open weights
- No
- Licence
- Proprietary
- Training cutoff
- February 2026
- Released
- 9 July 2026
- Status
- Legacy
- Type
- Reasoning model
What stands out
What its maker marketed at launch, and what people found later, each with its source.
Budget tier with 1M context
Fast, low-cost tier with 1.05M context and full reasoning-effort range.
Replacement for gpt-5-nano/mini snapshots
Found after launch
Named migration target for deprecated small GPT-5 snapshots.
Four assistants, one scale
GPT-5.6 Luna is added as a fifth row. Each row runs from what the model knows (graphite) through the months between its cutoff and its launch (hatched) to today (pink).
- GPT-6 Astra 271 at launch, 1,863 today
- Claude Opus 5.5 372 at launch, 1,795 today
- Gemini 4 Hydrogen 1,863 at launch, 1,889 today
- Grok 4.7 387 at launch, 1,829 today
- GPT-5.6 Luna 138 at launch, 1,919 today
Show as a table
| Model | Cutoff | Released | Missing at launch | Missing today |
|---|---|---|---|---|
| GPT-6 Astra | April 2026 | 3 September 2026 | 271 | 1,863 |
| Claude Opus 5.5 | June 2026 | 22 September 2026 | 372 | 1,795 |
| Gemini 4 Hydrogen | March 2026 | 12 November 2026 | 1,863 | 1,889 |
| Grok 4.7 | May 2026 | 21 September 2026 | 387 | 1,829 |
| GPT-5.6 Luna | February 2026 | 9 July 2026 | 138 | 1,919 |
Notes
Superseded by GPT-6 Luna (half the price) but still available.
curl https://api.openai.com/v1/responses \
-H "Authorization: Bearer $OPENAI_API_KEY" -H "Content-Type: application/json" \
-d '{"model":"gpt-5.6-luna","input":"Hello"}'
Sources: