# GPT-5.6 Luna vs Step 5 Preview - AI Model Comparison

- Page: https://opencode.ai/data/compare/openai/gpt-5-6-luna/stepfun/step-5-preview
- Updated: 2026-10-24T12:12:19.000Z

|  | GPT-5.6 Luna | Step 5 Preview |
| --- | --- | --- |
| Lab | OpenAI | StepFun |
| Context window | 1.1M | 1M |
| Max output | 128K | 1M |
| Input modalities | text, image, pdf | text, image, video |
| Reasoning | Yes | Yes |
| Tool calling | Yes | Yes |
| Open weights | No | Yes |
| Release date | 2026-07-09 | 2026-09-16 |
| Input price per 1M tokens | $0.20 | $1.06 |
| Output price per 1M tokens | $1.20 | $2.86 |
| Cached input price per 1M tokens | $0.02 | $0.05 |
| OpenCode tokens: past 2 months | 2.7T | 7.2T |
| Share of all tokens | 0.2% | 0.6% |
| Rank by tokens last week | #25 | #27 |
| Unique users | 344K | 114K |
| Weekly retention | 56.8% | 77.1% |

Model pages: [GPT-5.6 Luna](https://opencode.ai/data/openai/gpt-5-6-luna.md), [Step 5 Preview](https://opencode.ai/data/stepfun/step-5-preview.md)

## Methodology

- Updates: Aggregated every hour. Days and weeks use UTC.
- Tokens: Input, output, reasoning, and cached tokens for each request.
- Users and sessions: Approximate counts of distinct users and OpenCode sessions.
- Cost: Session cost is the average cost per OpenCode session. Token prices are list prices from the OpenCode model catalog.
- Retention: The share of a model's users in one week who use it again the next week.
- Citation: Cite OpenCode Data (opencode.ai/data) with the update time shown at the top of the page.