Grok 4.6 vs Solar Pro 4
Pricing, context window and real answers (August 2026)
Grok 4.6 (xAI) and Solar Pro 4 (Upstage), 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
 Grok 4.6 | Solar Pro 4 | |
|---|---|---|
| Provider | xAI | Upstage |
| Input (per 1M tokens) | ¥357.4 | ¥5.28 |
| Output (per 1M tokens) | ¥1,072.2 | ¥21.11 |
| Typical cost (1,000 in + 500 out tokens × 1,000 calls) | ¥894 | ¥16 |
| Context window | 500,000 tokens | 524,288 tokens |
| Release date | 8/12/2026 | 8/10/2026 |
| Input modalities | text, image, file | text |
| Arena · overall | #48 · ELO 1,461 | #173 · ELO 1,376 |
| Arena · Japanese | Unranked | Unranked |
| Arena · coding | #44 · ELO 1,510 | #140 · ELO 1,448 |
Prices are FastMetal's yen rates before tax. Arena ranks are as of the latest leaderboard scrape.
Which should you pick?
- On price, Solar Pro 4: ¥21.11 per 1M output tokens, 98% less than Grok 4.6.
- On the Overall arena board, Grok 4.6 ranks higher (#48; Solar Pro 4 is #173).
- On the Coding arena board, Grok 4.6 ranks higher (#44; Solar Pro 4 is #140).
- For long documents, Solar Pro 4: a 524,288-token context window against 500,000 for Grok 4.6.
- 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.
Grok 4.6
The word "strawberry" consists of the following letters in order:
s-t-r-a-w-b-e-r-r-y
Checking each one:
- s: not r
- t: not r
- r: yes (count = 1)
- a: not r
- w: not r
- b: not r
- e: not r
- r: yes (count = 2)
- r: yes (count = 3)
- y: not r
There are exactly 3 r's.
Final answer: 3
3.9s451 output tokens
Solar Pro 4
The word "strawberry" contains **3** 'r's. Here's the step-by-step breakdown:
1. **Spell out the word explicitly** to isolate each letter:
`s - t - r - a - w - b - e - r - r - y`
2. **Scan through the letters in order** and count every instance of the lowercase letter `r`:
- `s` → 0
- `t` → 0
- `r` → **1**
- `a` → 0
- `w` → 0
- `b` → 0
- `e` → 0
- `r` → **2**
- `r` → **3**
- `y` → 0
3. **Total the count**: The three `r`s appear at positions 3, 8, and 9 in the 10-letter word.
**Final count: 3**
11.4s215 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…
Grok 4.6
**The error happens because `users` is `undefined` when `.map()` is called.**
`UserList` destructures `{ users }` from its props. If the parent doesn't pass a `users` prop (or passes `undefined`/`null`), `users` is `undefined` and `undefined.map` throws.
This is extremely common when:
- Data is loaded asynchronously (initial render happens before the fetch finishes).
- The parent component forgets to pass the prop or uses a different name.
- The component is rendered before the data is ready (e.g. in a loading state).
### Quick fixes
**1. Default to an empty array (recommended)**
```jsx
function UserList({ users = [] }) {
return (
<ul>
{users.map(user => (
<li key={us…
20.3s598 output tokens
Solar Pro 4
### What's Causing the Error
The error `TypeError: Cannot read properties of undefined (reading 'map')` means that the `users` prop being passed to your `UserList` component is `undefined`. Since you're calling `.map()` directly on it, JavaScript throws an error because `undefined` doesn't have a `map` method.
This typically happens when:
- The parent component hasn't passed the `users` prop
- The prop is still loading (e.g., from an API call)
- The prop is conditionally undefined
---
### How to Fix It
You have a few options to handle this safely:
#### ✅ Option 1: Add a Default Prop Value (Recommended)
Provide a fallback empty array so `.map()` always has something to work with:
```j…
24.7s539 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):…
Grok 4.6
Here is a focused review of the function, followed by a cleaned-up version.
## Issues
**Imports inside the function**
`requests` and `time` should live at module level. Importing on every call is slower, hides dependencies, and is harder to mock in tests.
**Bare `except:`**
This swallows `KeyboardInterrupt`, `SystemExit`, and programming errors. Catch `requests.RequestException` (network/timeout/HTTP adapter errors) and JSON/`KeyError`/`TypeError` separately.
**Retrying the wrong things**
A 404 or 400 will never succeed on retry. Retry transient failures (timeouts, connection errors, 429, 5xx). Fail fast on most 4xx responses.
**Sleep after the last attempt**
On the final failur…
27.9s1770 output tokens
Solar Pro 4
Here’s a breakdown of the issues in the original function, followed by a refactored version and a detailed explanation of the improvements.
### 🔍 Key Issues in the Original Code
| Area | Problem |
|------|---------|
| **Import organization** | `import` inside the function is evaluated on every call. Imports should live at the top of the module. |
| **Exception handling** | Bare `except:` catches `SystemExit`, `KeyboardInterrupt`, and other fatal errors. Always catch specific exceptions (`requests.RequestException`). |
| **Loose equality** | `== True` is redundant and can cause subtle bugs. Use `if item["active"]:` or `.get()`. |
| **HTTP status handling** | Calling `.json()` only on `200`…
17.5s1172 output tokens
Frequently asked questions
- Which is cheaper, Grok 4.6 or Solar Pro 4?
- Per 1M output tokens, Grok 4.6 is ¥1,072.2 and Solar Pro 4 is ¥21.11 on FastMetal (yen, before tax), so Solar Pro 4 is cheaper.
- How do the context windows of Grok 4.6 and Solar Pro 4 compare?
- Grok 4.6 takes 500,000 tokens; Solar Pro 4 takes 524,288.
- Which ranks higher, Grok 4.6 or Solar Pro 4?
- Grok 4.6 ranks higher on the public arena (Grok 4.6 #48, Solar Pro 4 #173). Ranks move as the leaderboard updates.
- Can I use Grok 4.6 and Solar Pro 4 with the same API key?
- Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "grok-4.6" or "solar-pro4" 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 Grok 4.6 and Solar Pro 4 from the browser chat and the API. No monthly fee.