GPT-4o-mini vs Solar Mini 4
Pricing, context window and real answers (September 2026)
GPT-4o-mini (OpenAI) and Solar Mini 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
 GPT-4o-mini | Solar Mini 4 | |
|---|---|---|
| Provider | OpenAI | Upstage |
| Input (per 1M tokens) | ¥26.81 | ¥8.94 |
| Output (per 1M tokens) | ¥107.22 | ¥35.74 |
| Typical cost (1,000 in + 500 out tokens × 1,000 calls) | ¥80 | ¥27 |
| Context window | 128,000 tokens | 524,288 tokens |
| Release date | 7/18/2024 | 9/23/2026 |
| Input modalities | text, image, file | text |
| Throughput (p50) | — | — |
| Arena · overall | #251 · ELO 1,318 | Unranked |
| Arena · Japanese | #187 · ELO 1,250 | Unranked |
| Arena · coding | #259 · ELO 1,348 | Unranked |
Prices are FastMetal's yen rates before tax. Arena ranks are as of the latest leaderboard scrape.
Which should you pick?
- On price, Solar Mini 4: ¥35.74 per 1M output tokens, 67% less than GPT-4o-mini.
- For long documents, Solar Mini 4: a 524,288-token context window against 128,000 for GPT-4o-mini.
- 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-4o-mini
To count the number of 'r's in the word "strawberry," we can follow these steps:
1. **Identify the word**: We have the word "strawberry."
2. **Break down the letters**: Let's write out the letters in the word:
- s
- t
- r
- a
- w
- b
- e
- r
- r
- y
3. **Locate the 'r's**: Now, we need to look for the letter 'r' among these letters.
- In the list of letters, we can see:
- The first 'r' is in the 3rd position.
- The second 'r' is in the 8th position.
- The third 'r' is in the 9th position.
4. **Count the occurrences**: We check each position we identified:
- There are three occurrences of 'r' in the word "strawberry."
5. **Conclusion**:…
2.1s239 output tokens
Solar Mini 4
Sure! Let’s count the letter **'r'** in the word **'strawberry'** step by step.
**Step 1: Write out the word and its letters**
`s t r a w b e r r y`
**Step 2: Go through each letter one by one and check if it is 'r'**
1. `s` → not 'r'
2. `t` → not 'r'
3. `r` → **yes** (1st 'r')
4. `a` → not 'r'
5. `w` → not 'r'
6. `b` → not 'r'
7. `e` → not 'r'
8. `r` → **yes** (2nd 'r')
9. `r` → **yes** (3rd 'r')
10. `y` → not 'r'
**Step 3: Tally the total**
Total 'r' count = 3
**Final answer:** There are **3** letter 'r's in the word **'strawberry'**.
2.5s239 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-4o-mini
The error you're encountering, `TypeError: Cannot read properties of undefined (reading 'map')`, indicates that the `users` prop is `undefined` when you try to call the `map` method on it.
In your `UserList` component, you're attempting to use `users.map(...)`, but if the `users` prop is not provided or is `undefined`, this will throw an error.
### Fixing the Error
1. **Default Props**: You can set a default value for the `users` prop to prevent the error when it is `undefined`.
```jsx
function UserList({ users = [] }) { // Default to an empty array
return (
<ul>
{users.map(user => <li key={user.id}>{user.name}</li>)}
</ul>
);
}
```…
5.0s511 output tokens
Solar Mini 4
This error occurs because the `users` prop being passed to your `UserList` component is `undefined` (or the component is rendered without that prop), and your code tries to call `.map()` on it.
### 🔍 Why this happens
In JavaScript, `undefined.map` is not a function, so calling it throws:
```
TypeError: Cannot read properties of undefined (reading 'map')
```
This commonly happens when:
- The parent component doesn't pass the `users` prop at all
- The parent passes `users` as `undefined`, `null`, or a non-array value (like a promise, object, or string)
- Data hasn't finished loading yet (e.g., fetched from an API asynchronously)
### ✅ How to fix it
The most robust solution is to provide a…
9.2s701 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):…
GPT-4o-mini
Your Python function, `get_data`, essentially performs a GET request, handles retries on failure, and processes the response JSON to return a filtered list of dictionaries. Below, I've highlighted several improvements regarding readability, performance, and best practices:
1. **Avoid blanket exceptions**: It’s best practice to specify which exceptions you expect, allowing for better debugging and error handling.
2. **Use `requests` built-in exception handling**: Handle specific requests exceptions, such as `requests.exceptions.RequestException`.
3. **Improve condition checks**: Check for `item['active']` directly instead of comparing to `True`, which is more Pythonic.
4. **Use `time.sl…
8.8s628 output tokens
Solar Mini 4
Here’s a reviewed version of your function, followed by a breakdown of the improvements:
```python
import time
import requests
from requests.adapters import HTTPAdapter
from urllib3.util.retry import Retry
def get_data(url: str, retries: int = 3) -> list[dict]:
"""
Fetch JSON from a URL and return a list of active items with name/id.
Args:
url: The endpoint to request.
retries: Number of retry attempts on failure.
Returns:
A list of dicts matching {'name': str, 'id': any} for active items.
"""
if retries < 1:
raise ValueError("retries must be at least 1")
session = requests.Session()
retry_strategy = Retry(
total=re…
10.8s1278 output tokens
Frequently asked questions
- Which is cheaper, GPT-4o-mini or Solar Mini 4?
- Per 1M output tokens, GPT-4o-mini is ¥107.22 and Solar Mini 4 is ¥35.74 on FastMetal (yen, before tax), so Solar Mini 4 is cheaper.
- How do the context windows of GPT-4o-mini and Solar Mini 4 compare?
- GPT-4o-mini takes 128,000 tokens; Solar Mini 4 takes 524,288.
- Can I use GPT-4o-mini and Solar Mini 4 with the same API key?
- Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "gpt-4o-mini" or "solar-mini4" 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-4o-mini and Solar Mini 4 from the browser chat and the API. No monthly fee.