Gemini 3.1 Pro Preview vs Solar Mini 4
Pricing, context window and real answers (September 2026)
Gemini 3.1 Pro Preview (Google) 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
 Gemini 3.1 Pro Preview | Solar Mini 4 | |
|---|---|---|
| Provider | Upstage | |
| Input (per 1M tokens) | ¥357.4 | ¥8.94 |
| Output (per 1M tokens) | ¥2,144.4 | ¥35.74 |
| Typical cost (1,000 in + 500 out tokens × 1,000 calls) | ¥1,430 | ¥27 |
| Context window | 1,048,576 tokens | 524,288 tokens |
| Release date | 2/19/2026 | 9/23/2026 |
| Input modalities | audio, file, image, text, video | text |
| Throughput (p50) | — | — |
| Arena · overall | #15 · ELO 1,487 | Unranked |
| Arena · Japanese | #9 · ELO 1,494 | Unranked |
| Arena · coding | #28 · ELO 1,520 | 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, 98% less than Gemini 3.1 Pro Preview.
- For long documents, Gemini 3.1 Pro Preview: a 1,048,576-token context window against 524,288 for Solar Mini 4.
- 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.
Gemini 3.1 Pro Preview
There are **3** 'r's in the word 'strawberry'.
Here is the step-by-step breakdown of the spelling:
1. **s** - not an 'r'
2. **t** - not an 'r'
3. **r** - **1st 'r'**
4. **a** - not an 'r'
5. **w** - not an 'r'
6. **b** - not an 'r'
7. **e** - not an 'r'
8. **r** - **2nd 'r'**
9. **r** - **3rd 'r'**
10. **y** - not an 'r'
Therefore, the total count is 3.
5.3s503 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…
Gemini 3.1 Pro Preview
### The Cause
This error occurs because the `users` prop being passed to your `UserList` component is currently `undefined`.
In JavaScript, you can only use the `.map()` method on arrays. Because `users` is `undefined` (often due to data not finishing an API fetch yet, or the parent component forgetting to pass the prop), Node/React throws an error when it tries to read `.map`.
### How to Fix It
You can fix this in a few different ways, depending on how you want your application to behave.
#### Fix 1: Assign a Default Value (Recommended)
The cleanest way to handle this is to assign a default empty array to `users` in your component's parameters. If `users` is undefined, it defaults to…
13.2s1511 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):…
Gemini 3.1 Pro Preview
Here is a review of your function. While the original code works, there are several areas where it can be improved regarding **best practices**, **readability**, and **performance**.
### 1. Refactored Code
Here is the improved version of your function. I will explain the specific changes below.
```python
import time
import requests
import logging
from typing import Any
# Optional: Set up a logger
logger = logging.getLogger(__name__)
def get_data(url: str, retries: int = 3, delay: int = 2, timeout: int = 10) -> list[dict[str, Any]]:
"""
Fetches JSON data from a URL and extracts active items.
Args:
url: The API endpoint to fetch data from.
retries: Number o…
23.6s3094 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, Gemini 3.1 Pro Preview or Solar Mini 4?
- Per 1M output tokens, Gemini 3.1 Pro Preview is ¥2,144.4 and Solar Mini 4 is ¥35.74 on FastMetal (yen, before tax), so Solar Mini 4 is cheaper.
- How do the context windows of Gemini 3.1 Pro Preview and Solar Mini 4 compare?
- Gemini 3.1 Pro Preview takes 1,048,576 tokens; Solar Mini 4 takes 524,288.
- Can I use Gemini 3.1 Pro Preview and Solar Mini 4 with the same API key?
- Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "gemini-3.1-pro-preview" 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 Gemini 3.1 Pro Preview and Solar Mini 4 from the browser chat and the API. No monthly fee.