Claude Sonnet 4.6 vs GLM 5.1
Pricing, context window and real answers (August 2026)
Claude Sonnet 4.6 (Anthropic) and GLM 5.1 (Z.ai), 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 Sonnet 4.6 |  GLM 5.1 | |
|---|---|---|
| Provider | Anthropic | Z.ai |
| Input (per 1M tokens) | ¥554.4 | ¥250.18 |
| Output (per 1M tokens) | ¥2,772 | ¥786.28 |
| Typical cost (1,000 in + 500 out tokens × 1,000 calls) | ¥1,940 | ¥643 |
| Context window | 1,000,000 tokens | 204,800 tokens |
| Release date | 2/17/2026 | 4/7/2026 |
| Input modalities | text, image | text |
| Arena · overall | #32 · ELO 1,472 | #41 · ELO 1,466 |
| Arena · Japanese | #41 · ELO 1,438 | #49 · ELO 1,430 |
| Arena · coding | #14 · ELO 1,528 | #36 · ELO 1,514 |
Prices are FastMetal's yen rates before tax. Arena ranks are as of the latest leaderboard scrape.
Which should you pick?
- On price, GLM 5.1: ¥786.28 per 1M output tokens, 72% less than Claude Sonnet 4.6.
- On the Overall arena board, Claude Sonnet 4.6 ranks higher (#32; GLM 5.1 is #41).
- On the Japanese arena board, Claude Sonnet 4.6 ranks higher (#41; GLM 5.1 is #49).
- On the Coding arena board, Claude Sonnet 4.6 ranks higher (#14; GLM 5.1 is #36).
- For long documents, Claude Sonnet 4.6: a 1,000,000-token context window against 204,800 for GLM 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 Sonnet 4.6
## Counting the letter 'r' in 'strawberry'
Let me go through the word letter by letter:
| Position | Letter | Is it 'r'? |
|----------|--------|------------|
| 1 | s | No |
| 2 | t | No |
| 3 | r | ✅ Yes |
| 4 | a | No |
| 5 | w | No |
| 6 | b | No |
| 7 | e | No |
| 8 | r | ✅ Yes |
| 9 | r | ✅ Yes |
| 10 | y | No |
## Result
There are **3 r's** in 'strawberry'.
2.2s181 output tokens
GLM 5.1
There are **3** 'r's in the word "strawberry".
Here is the step-by-step reasoning:
1. Let's break down the word "strawberry" letter by letter: s - t - r - a - w - b - e - r - r - y
2. Now, let's check each letter one by one to see if it is an 'r':
- **s**: not an 'r'
- **t**: not an 'r'
- **r**: this is the 1st 'r'
- **a**: not an 'r'
- **w**: not an 'r'
- **b**: not an 'r'
- **e**: not an 'r'
- **r**: this is the 2nd 'r'
- **r**: this is the 3rd 'r'
- **y**: not an 'r'
3. Counting them up, there are three 'r's in total (in the 3rd, 8th, and 9th positions).
7.3s565 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 Sonnet 4.6
## Problem Analysis
The error occurs because `users` is `undefined` when the component renders. You're calling `.map()` on `undefined`, which throws a `TypeError`.
**Common causes:**
- The prop isn't passed by the parent component
- Data is still loading asynchronously when the component first renders
- The parent passes `undefined` or a misspelled prop name
---
## Solutions
### Option 1: Default Parameter Value (Simplest Fix)
```javascript
function UserList({ users = [] }) {
return (
<ul>
{users.map(user => <li key={user.id}>{user.name}</li>)}
</ul>
);
}
```
This assigns an empty array if `users` is `undefined`, so `.map()` always has an array to work with.
---
###…
9.4s798 output tokens
GLM 5.1
### What is causing the error?
The error `TypeError: Cannot read properties of undefined (reading 'map')` means you are trying to call the `.map()` method on a variable that is `undefined`.
In your code, the variable is `users`. When the `UserList` component renders, the `users` prop is `undefined`, so `undefined.map()` throws an error.
### Why is `users` undefined?
This usually happens for one of two reasons:
1. **You forgot to pass the prop:** The parent component rendering `<UserList />` is not passing the `users` attribute (e.g., `<UserList />` instead of `<UserList users={myUsers} />`).
2. **Async Data Fetching:** You are fetching the users from an API. On the initial render, befor…
45.0s1680 output tokens
Code Review
Please review the following Python function and suggest improvements for readability, performance, and best practices: def get_data(url, retries=3): import requests import time for i in range(retries):…
Claude Sonnet 4.6
## Code Review and Improvements
### Issues Identified
1. **Imports inside function** – should be at module level
2. **Bare `except`** – catches everything including `KeyboardInterrupt`, `SystemExit`
3. **`== True` comparison** – not Pythonic
4. **No logging/error visibility** – silent failures make debugging hard
5. **Magic numbers** – hardcoded `2`, `10` with no explanation
6. **No distinction between retriable/non-retriable errors** – e.g., 404 should not be retried
7. **Inefficient list building** – list comprehension is cleaner
8. **No exponential backoff** – fixed sleep is naive for real-world retry logic
9. **Missing type hints and docstring**
---
### Improved Version
```python
im…
14.4s1099 output tokens
GLM 5.1
Here is a review of your function, broken down by areas for improvement, followed by a refactored version of the code.
### Key Areas for Improvement
1. **Imports Inside the Function:**
Placing `import` statements inside a function is generally discouraged in Python. It slows down the function execution every time it is called, and it violates PEP 8 (the Python style guide). Imports should always be at the top of the module.
2. **Bare `except` Clause:**
Using a bare `except:` catches *everything*, including `KeyboardInterrupt` and `SystemExit`, which makes it hard to terminate a hanging program. You should catch specific exceptions (like `requests.exceptions.RequestException`).
3. *…
70.3s2854 output tokens
Frequently asked questions
- Which is cheaper, Claude Sonnet 4.6 or GLM 5.1?
- Per 1M output tokens, Claude Sonnet 4.6 is ¥2,772 and GLM 5.1 is ¥786.28 on FastMetal (yen, before tax), so GLM 5.1 is cheaper.
- How do the context windows of Claude Sonnet 4.6 and GLM 5.1 compare?
- Claude Sonnet 4.6 takes 1,000,000 tokens; GLM 5.1 takes 204,800.
- Which ranks higher, Claude Sonnet 4.6 or GLM 5.1?
- Claude Sonnet 4.6 ranks higher on the public arena (Claude Sonnet 4.6 #41, GLM 5.1 #49). Ranks move as the leaderboard updates.
- Can I use Claude Sonnet 4.6 and GLM 5.1 with the same API key?
- Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "anthropic-claude-sonnet-4-6" or "glm-5.1" 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 Sonnet 4.6 and GLM 5.1 from the browser chat and the API. No monthly fee.