The short answer
GPT-5.6 Luna is an OpenAI model priced at $0.1 per million input tokens and $0.6 per million output tokens, with a 1M token context window. One standard answer, meaning 1,000 tokens in and 500 tokens out, costs $0.0004. Inside Whizi it costs 1 credit per message and needs the Starter plan or above.
That makes it one of the cheaper models in the catalogue: 71 of the 89 priced models cost more per answer, and 17 cost less.
What GPT-5.6 Luna costs
List rates are what the provider charges per token. The cost of one standard answer is the more useful number, because it prices the same unit of work across every model regardless of how each one is billed.
| Input, per million tokens | $0.1 |
| Output, per million tokens | $0.6 |
| One standard answer | $0.0004 |
| One thousand answers | $0.4000 |
| Context window | 1M tokens |
| Credits per message in Whizi | 1 |
| Minimum Whizi plan | Starter |
| Rank by cost, of 89 priced models | 18 |
Prices are the published OpenAI rates as carried by OpenRouter, last refreshed 2026-08-08. The full dataset covering all 100 models from 28 providers is the AI model cost index, which is free to reuse with attribution.
What it costs inside Whizi
Whizi meters messages in credits rather than tokens, and GPT-5.6 Luna is charged at 1 credit per message. The cost does not change with the length of your message or the length of the answer, so a one line question and a long document analysis cost the same.
| Plan | Price per month | Monthly credits | Messages on this model |
|---|---|---|---|
| Starter | $15.99, or $10.99 billed yearly | 400 | 400 |
| Pro | $29.99, or $19.99 billed yearly | 2,000 | 2,000 |
| Powerhouse | $49.99, or $34.99 billed yearly | 8,000 | 8,000 |
GPT-5.6 Luna is included on every plan, including Starter. The Starter models are the ones that cost 1 credit per message, which is what makes a 400 credit allowance go a long way. See plans and limits.
How it compares on price
Against the cheapest model in the index, Ling-2.6-flash at $0.000025 per answer, GPT-5.6 Luna costs 16 times more. Against the median, GLM 4.6 at $0.0015, it costs 3.8 times less.
Its nearest neighbours from OpenAI:
| Model | One answer | Context | Credits |
|---|---|---|---|
| GPT-5.6 Luna (this page) | $0.0004 | 1M | 1 |
| GPT-5.4 Nano | $0.0008 | 400K | 2 |
| GPT-5.4 Mini | $0.0030 | 400K | 4 |
| GPT-5.6 Terra | $0.0040 | 1M | 4 |
It is the cheapest OpenAI model in the priced index, so within this provider there is nothing to route down to.
The context window in practice
GPT-5.6 Luna accepts 1M tokens of context, which is roughly 1600 pages of text. That is well above the median for the priced catalogue.
Advertised context and usable context are not the same thing. Recall tends to degrade before the stated limit is reached, particularly for material in the middle of a long input, so the practical test is to upload a long document and ask about something buried halfway through rather than trusting the number.
The number matters most when you are working from your own files. If a document is too long for the model you picked, switching to a larger-context model in the same conversation carries the thread across, so you are not starting over. See switching models mid-conversation.
- Input $0.1 and output $0.6 per million tokens
- $0.0004 for one standard answer, $0.4000 for a thousand
- 1M token context window
- 1 credit per message inside Whizi
- Requires the Starter plan or above
- Ranks 18 of 89 priced models by cost per answer
Frequently asked questions
How much does GPT-5.6 Luna cost?
$0.1 per million input tokens and $0.6 per million output tokens at list rates, which works out to $0.0004 for one standard answer of 1,000 tokens in and 500 out, or $0.4000 for a thousand of them. Inside Whizi it is 1 credit per message on a monthly allowance, rather than metered per token.
Which Whizi plan includes GPT-5.6 Luna?
Every plan, including Starter at $15.99 per month or $10.99 billed yearly. At 1 credit per message, a Starter allowance of 400 credits covers 400 messages on it.
What is the context window of GPT-5.6 Luna?
1M tokens, which is roughly 1600 pages of text and sits well above the median for the priced catalogue. Treat that as the ceiling rather than the working figure: recall usually degrades before the stated limit, especially for content in the middle of a long input.
Is GPT-5.6 Luna expensive compared to other models?
It ranks 18 of 89 priced models by cost per answer, so 71 cost more and 17 cost less. The spread across the whole catalogue is about 4800 times from cheapest to priciest, which is far wider than most people assume, so "expensive" only means anything relative to the specific alternative you would otherwise use.