GPT-5.6 Luna — API Pricing & Benchmarks
GPT-5.6 Luna is OpenAI's previous-generation reasoning model, released in 2026-07. The API costs $0.20 per 1M input tokens and $1.20 per 1M output tokens ($0.45 blended at a 3:1 ratio), with cached input at $0.02. It supports a 1.1M-token context window. On the independently measured Artificial Analysis Intelligence Index it scores 37.3, ranking #28 of 72 models tracked on this site, with a median output speed of 128 tokens/sec. Pricing was cut on 2026-08-09 (previously $1.00/$6.00 per 1M tokens).
Explore provider routes and additional benchmark sources for GPT-5.6 Luna
| Provider | OpenAI |
| Input price / 1M tokens | $0.20 |
| Output price / 1M tokens | $1.20 |
| Cached input / 1M tokens | $0.02 |
| Blended price (3:1) | $0.45 |
| Context window | 1.1M |
| Max output tokens | 128K |
| Knowledge cutoff | 2026-02 |
| License | proprietary |
| Input modalities | T+I |
| Output speed (tok/s) | 128 |
| Released | 2026-07 |
| Artificial Analysis Intelligence Index | 37.3 |
| LMArena Elo | 1430 |
| GPQA Diamond | 91.1% |
| Humanity's Last Exam | 39.5% |
Where GPT-5.6 Luna fits
On a blended 3:1 basis GPT-5.6 Luna costs $0.45 per 1M tokens, cheaper than 83% of the 84 priced models in this index. It is a previous-generation model: usually only worth choosing if you have an existing integration, negotiated pricing, or need its specific behavior, since newer siblings offer better price-performance. Cached input is priced at $0.02 (90% below standard input), which rewards prompt structures with long stable prefixes — see our caching guide.
Price history
| Period | Input $/1M | Output $/1M | Cached $/1M |
|---|---|---|---|
| 2026-07-18 → 2026-08-09 | $1.00 | $6.00 | $0.10 |
| 2026-08-09 → current | $0.20 | $1.20 | $0.02 |
List-price changes recorded by this site. The full dataset is public: price-history.json (CC BY 4.0).
Alternatives at a similar price
- Codestral 25.08 (Mistral AI) — $0.45/1M blended
- GPT-5.4 nano (OpenAI) — $0.46/1M blended, AA Index 20.7
- GLM-4.5-Air (Zhipu AI (Z.ai)) — $0.43/1M blended, AA Index 11.1
- DeepSeek V4.1 Flash (DeepSeek) — $0.52/1M blended, AA Index 39.5
About OpenAI
OpenAI builds the GPT series. The GPT-6 generation (September 2026) ships in three sizes — Astra (flagship, $10/$50), Sol ($2/$10) and Luna ($0.10/$0.50) — that share a 1.05M-token context window and the same tooling, so teams can move workloads between price points without changing integration code. The GPT-5.6 models remain on sale as the previous generation.