GPT-5.6 Luna vs Qwen3.8 2.4T A95B
Pricing, context window and real answers (August 2026)
GPT-5.6 Luna (OpenAI) and Qwen3.8 2.4T A95B (Qwen), compared as you can actually call them on FastMetal. Both are served from the same OpenAI-compatible endpoint and API key; switching is a change to the model string.
Specs and pricing
 GPT-5.6 Luna |  Qwen3.8 2.4T A95B | |
|---|---|---|
| Provider | OpenAI | Qwen |
| Input (per 1M tokens) | ¥35.74 | ¥351.83 |
| Output (per 1M tokens) | ¥214.44 | ¥1,055.5 |
| Typical cost (1,000 in + 500 out tokens × 1,000 calls) | ¥143 | ¥880 |
| Context window | 1,050,000 tokens | 1,048,576 tokens |
| Release date | 7/9/2026 | 8/12/2026 |
| Input modalities | file, image, text | text |
| Arena · overall | #63 · ELO 1,452 | Unranked |
| Arena · Japanese | #36 · ELO 1,444 | Unranked |
| Arena · coding | #69 · ELO 1,496 | Unranked |
Prices are FastMetal's yen rates before tax. Arena ranks are as of the latest leaderboard scrape.
Which should you pick?
- On price, GPT-5.6 Luna: ¥214.44 per 1M output tokens, 80% less than Qwen3.8 2.4T A95B.
- For long documents, GPT-5.6 Luna: a 1,050,000-token context window against 1,048,576 for Qwen3.8 2.4T A95B.
- If in doubt, try both on the same key. Switching is a change to the model string, and each is billed at its own rate.
Real answers to the same prompts
Exactly what the FastMetal gateway returned, side by side. Not benchmark scores: actual output.
Count the number of 'r's in 'strawberry'
Count the number of 'r's in 'strawberry'. Explain your reasoning step by step.
GPT-5.6 Luna
The word **“strawberry”** is spelled:
**s – t – r – a – w – b – e – r – r – y**
The letter **“r”** appears at positions **3, 8, and 9**.
**Answer: 3**
3.0s120 output tokens
Qwen3.8 2.4T A95B
To count the number of **“r”**s in **“strawberry”**, spell it out letter by letter:
**s t r a w b e r r y**
Now check each letter:
1. s — not r
2. t — not r
3. r — yes, count 1
4. a — not r
5. w — not r
6. b — not r
7. e — not r
8. r — yes, count 2
9. r — yes, count 3
10. y — not r
So there are **3** “r”s in **strawberry**.
1.3s203 output tokens
Debug This Error
I'm getting the following error in my Node.js application: TypeError: Cannot read properties of undefined (reading 'map') at UserList (/app/components/UserList.js:12:25) at renderWithHooks (/app/node_modules/rea…
GPT-5.6 Luna
`users` is `undefined` when `UserList` renders, so calling `.map()` on it fails. `.map()` only exists on arrays.
Common causes include:
- The parent does not pass a `users` prop.
- The prop name differs, such as `userList` instead of `users`.
- Users are loaded asynchronously and are initially undefined.
- The API response has a different shape, such as `{ data: [...] }`.
### Provide a default value
```jsx
function UserList({ users = [] }) {
return (
<ul>
{users.map(user => (
<li key={user.id}>{user.name}</li>
))}
</ul>
);
}
```
The parent should pass an array:
```jsx
<UserList users={users} />
```
If the list comes from state, initialize it as an empty…
4.8s507 output tokens
Qwen3.8 2.4T A95B
The error happens because `users` is `undefined` when React tries to render this line:
```js
{users.map(user => <li key={user.id}>{user.name}</li>)}
```
JavaScript cannot call `.map()` on `undefined`.
In your component:
```js
function UserList({ users }) {
return (
<ul>
{users.map(user => <li key={user.id}>{user.name}</li>)}
</ul>
);
}
```
React expects `users` to be an array, but something is rendering `<UserList />` without providing a valid `users` prop.
---
## Common causes
### 1. The parent component is not passing `users`
For example:
```js
<UserList />
```
Instead of:
```js
<UserList users={users} />
```
---
### 2. The data has not loaded yet
If `users…
10.9s1318 output tokens
Professional Email
Write a professional email to a client explaining that the project delivery will be delayed by two weeks due to unexpected technical challenges discovered during integration testing. The tone should be apologetic but con…
GPT-5.6 Luna
**Subject:** Project Delivery Timeline Update
Dear [Client Name],
I’m writing to provide an update on the project delivery timeline. During integration testing, our team identified several unexpected technical challenges affecting system compatibility and performance. To ensure the final product meets the agreed quality and reliability standards, we need to extend the delivery date by two weeks.
The revised timeline is as follows:
- **[Original Delivery Date]:** Completion of integration testing and issue analysis
- **[Date]:** Implementation and validation of corrective fixes
- **[Date]:** Full regression testing and performance verification
- **[Revised Delivery Date]:** Final de…
4.3s337 output tokens
Qwen3.8 2.4T A95B
Subject: Updated Project Timeline – Revised Delivery Date
Dear [Client Name],
I hope this message finds you well.
I’m writing to provide an important update regarding the delivery timeline for [Project Name]. During our recent integration testing phase, we identified several unexpected technical challenges that require additional resolution to ensure the final deliverable meets the quality and performance standards we committed to.
After carefully reviewing the scope of these items with our technical team, we have determined that the project delivery will need to be extended by two weeks. I sincerely apologize for any inconvenience this may cause. Please be assured that we are taking imm…
4.6s449 output tokens
Frequently asked questions
- Which is cheaper, GPT-5.6 Luna or Qwen3.8 2.4T A95B?
- Per 1M output tokens, GPT-5.6 Luna is ¥214.44 and Qwen3.8 2.4T A95B is ¥1,055.5 on FastMetal (yen, before tax), so GPT-5.6 Luna is cheaper.
- How do the context windows of GPT-5.6 Luna and Qwen3.8 2.4T A95B compare?
- GPT-5.6 Luna takes 1,050,000 tokens; Qwen3.8 2.4T A95B takes 1,048,576.
- Can I use GPT-5.6 Luna and Qwen3.8 2.4T A95B with the same API key?
- Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "gpt-5.6-luna" or "qwen3.8-2.4t-a95b" as the model. Each is billed at its own rate from the same prepaid balance.
Try both on one API key
Create an account and add credit to call GPT-5.6 Luna and Qwen3.8 2.4T A95B from the browser chat and the API. No monthly fee.