GPT-5.6 Luna: what it costs to run
The price OpenAI lists for GPT-5.6 Luna, what a support reply, a document summary and an agent task cost at it, and where that puts it among 37 models.
US dollars per million tokens, standard rate, shortest context band.
- 1,000 support replies
- $1.08
- Cached input
- $0.02
- Context window
- 1,050,000 tokens
- Released
- 9 Jul 2026
- Weights
- Closed
From OpenAI’s own pages, 22 September 2026.
GPT-5.6 Luna costs $0.20 per million input tokens and $1.20 per million output tokens on OpenAI’s own API, and $0.02 for cached input. At those prices 1,000 support replies cost $1.08, the 5th cheapest of 33 priced models on our list.
What a job costs
Three jobs, 1,000 runs of each, at the list price above, and where each puts GPT-5.6 Luna among the 33 models with a list price.
| Job | 1,000 runs | Among 33 |
|---|---|---|
| Support reply3,000 in, 400 out. | $1.08 | 5th cheapest |
| Document summary25,000 in, 1,000 out. | $6.20 | 5th cheapest |
| Agent task80,000 in (70,000 cached), 3,000 out. | $7.00 | 2nd cheapest |
The token counts are ours, chosen to look like real work; the prices are OpenAI’s. All three jobs stay under 200,000 tokens a request, below every long-context surcharge on the list.
GPT-5.6 Luna on real small-business tasks
What the AIGROW benchmark measured when GPT-5.6 Luna was given 20 office tasks, each marked pass or fail by fixed checks.
- Success rate
- 80% of 20 runs passed (95% interval 58 to 92%), 18th of 36 models.
- Cost per 1,000 passes
- $0.677, failed runs included, worked from list price.
- Answer time
- 28 s median, 34 s at the 90th percentile.
- Strongest and weakest
- Appointment scheduling (100% passed) and quotes (50%).
The small print
What the base rate above leaves out, copied from the maker’s pages: surcharges, discounts, promotions and cache pricing.
Nano tier of the 5.6 family. Price cut 80% on 2026-07-30. Requests above 272K input tokens bill 2x input and 1.5x output ($0.40 / $1.80). Cache write $0.25. Batch and Flex 50% off. Data residency adds 10%.
GPT-5.6 Luna against the models it is weighed with
Each comparison puts both list prices side by side and costs the same three jobs on each.
- vs Gemini 3.5 Flash-Lite
- The newest budget models from OpenAI and Google, both aimed at high-volume tasks.
- vs Gemini 3.1 Flash-Lite
- OpenAI's nano tier against Google's cheapest Gemini, close on price.
- vs Claude Haiku 4.5
- Anthropic's small model costs five times Luna on input, so it has to earn the difference.
- vs GPT-5.4 mini
- The older mini against the newer nano tier, which now costs less than a third as much.
- vs GPT-5.4 nano
- The same input price across a model generation, so the quality change is the whole story.
- vs DeepSeek V4.1 Flash
- Two low-cost APIs for bulk work, with DeepSeek cheaper again off-peak.
- vs Mistral Small 4
- Mistral's open-weight small model against OpenAI's nano tier, both near the bottom of the price range.
Other OpenAI models
| Model | Input | Output | Context | 1,000 replies |
|---|---|---|---|---|
| GPT-5.4 nanoOpenAI | $0.20 | $1.25 | 400K | $1.10 |
| GPT-5.4 miniOpenAI | $0.75 | $4.50 | 400K | $4.05 |
| GPT-5.6 TerraOpenAI | $2.00 | $12.00 | 1.05M | $10.80 |
| GPT-5.6 SolOpenAI | $4.00 | $20.00 | 1.05M | $20.00 |
| GPT-5.5OpenAI | $5.00 | $30.00 | 1.05M | $27.00 |
| GPT-6 AstraOpenAI | $10.00 | $50.00 | 1.05M | $50.00 |
| gpt-oss-120bOpenAI · open weights | No list price | · | 131K | · |
Where the price comes from
Read on 22 September 2026. Each price is the standard rate for the shortest context band, with no batch or priority discount; long-context surcharges, batch rates and promotions are in each model’s small print. No price was taken from a reseller.
Run GPT-5.6 Luna for a quarter of its list price
AIGROW API credit covers GPT-5.6 Luna and is metered at the list price above: $25 buys $100 of usage.
Prices checked 22 September 2026