Claude Fable 5.1 vs Qwen3.8 2.4T A95B
Pricing, context window and real answers (September 2026)
Claude Fable 5.1 (Anthropic) 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
 Claude Fable 5.1 |  Qwen3.8 2.4T A95B | |
|---|---|---|
| Provider | Anthropic | Qwen |
| Input (per 1M tokens) | ¥1,787 | ¥351.83 |
| Output (per 1M tokens) | ¥8,935 | ¥1,055.5 |
| Typical cost (1,000 in + 500 out tokens × 1,000 calls) | ¥6,255 | ¥880 |
| Context window | 1,000,000 tokens | 1,048,576 tokens |
| Release date | 9/1/2026 | 8/12/2026 |
| Input modalities | text, image, file | text |
| Arena · overall | #3 · ELO 1,504 | Unranked |
| Arena · Japanese | Unranked | Unranked |
| Arena · coding | #34 · ELO 1,517 | Unranked |
Prices are FastMetal's yen rates before tax. Arena ranks are as of the latest leaderboard scrape.
Which should you pick?
- On price, Qwen3.8 2.4T A95B: ¥1,055.5 per 1M output tokens, 88% less than Claude Fable 5.1.
- For long documents, Qwen3.8 2.4T A95B: a 1,048,576-token context window against 1,000,000 for Claude Fable 5.1.
- 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.
Claude Fable 5.1
**Step 1: Write out the word letter by letter.**
s - t - r - a - w - b - e - r - r - y
**Step 2: Number each position.**
1. s
2. t
3. **r**
4. a
5. w
6. b
7. e
8. **r**
9. **r**
10. y
**Step 3: Identify which positions contain 'r'.**
- Position 3: r (in "str-")
- Position 8: r (in "-ber-")
- Position 9: r (in "-rry")
**Step 4: Count them.**
3 + 1 + 1 = **3**
**Answer: There are 3 'r's in "strawberry."**
A helpful way to check: split the word into its parts — "straw" (1 r) + "berry" (2 r's) = 3 r's total.
7.9s259 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…
Claude Fable 5.1
The error means that when `UserList` rendered, the `users` prop was `undefined`, so calling `.map()` on it failed. This typically happens because:
1. **The parent isn't passing the prop** (or misspelled it, e.g. `<UserList user={...} />`), or
2. **The data hasn't loaded yet.** A common pattern is fetching users in a `useEffect` and storing them in state whose initial value is `undefined` (e.g. `useState()`), so the first render happens before the data arrives.
**Fixes**
Give the prop a default value so the component is safe to render with no data:
```jsx
function UserList({ users = [] }) {
return (
<ul>
{users.map(user => <li key={user.id}>{user.name}</li>)}
</ul>
);
}…
10.8s564 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…
Claude Fable 5.1
**Subject:** Revised Delivery Timeline for [Project Name] – Updated Completion Date [New Date]
Dear [Client Name],
I'm writing to inform you that the delivery of [Project Name] will be delayed by two weeks, moving the completion date from [Original Date] to [New Date]. I sincerely apologize for this change and for any disruption it may cause to your planning. I want to be fully transparent about what happened, what we're doing about it, and why we're confident in the revised date.
**What we found**
During integration testing last week, our team identified [brief, plain-language description – e.g., a data synchronization conflict between the new payment module and your existing inventory…
17.3s1019 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, Claude Fable 5.1 or Qwen3.8 2.4T A95B?
- Per 1M output tokens, Claude Fable 5.1 is ¥8,935 and Qwen3.8 2.4T A95B is ¥1,055.5 on FastMetal (yen, before tax), so Qwen3.8 2.4T A95B is cheaper.
- How do the context windows of Claude Fable 5.1 and Qwen3.8 2.4T A95B compare?
- Claude Fable 5.1 takes 1,000,000 tokens; Qwen3.8 2.4T A95B takes 1,048,576.
- Can I use Claude Fable 5.1 and Qwen3.8 2.4T A95B with the same API key?
- Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "anthropic-claude-fable-5-1" 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 Claude Fable 5.1 and Qwen3.8 2.4T A95B from the browser chat and the API. No monthly fee.