Gemini 3.1 Pro Preview vs Solar Pro 4
Pricing, context window and real answers (September 2026)
Gemini 3.1 Pro Preview (Google) 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
 Gemini 3.1 Pro Preview | Solar Pro 4 | |
|---|---|---|
| Provider | Upstage | |
| Input (per 1M tokens) | ¥357.4 | ¥16.08 |
| Output (per 1M tokens) | ¥2,144.4 | ¥64.33 |
| Typical cost (1,000 in + 500 out tokens × 1,000 calls) | ¥1,430 | ¥48 |
| Context window | 1,048,576 tokens | 524,288 tokens |
| Release date | 2/19/2026 | 8/10/2026 |
| Input modalities | audio, file, image, text, video | text |
| Throughput (p50) | — | — |
| Arena · overall | #15 · ELO 1,487 | #177 · ELO 1,376 |
| Arena · Japanese | #9 · ELO 1,494 | Unranked |
| Arena · coding | #28 · ELO 1,520 | #144 · ELO 1,449 |
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: ¥64.33 per 1M output tokens, 97% less than Gemini 3.1 Pro Preview.
- On the Overall arena board, Gemini 3.1 Pro Preview ranks higher (#15; Solar Pro 4 is #177).
- On the Coding arena board, Gemini 3.1 Pro Preview ranks higher (#28; Solar Pro 4 is #144).
- For long documents, Gemini 3.1 Pro Preview: a 1,048,576-token context window against 524,288 for Solar Pro 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 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…
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 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):…
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 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, Gemini 3.1 Pro Preview or Solar Pro 4?
- Per 1M output tokens, Gemini 3.1 Pro Preview is ¥2,144.4 and Solar Pro 4 is ¥64.33 on FastMetal (yen, before tax), so Solar Pro 4 is cheaper.
- How do the context windows of Gemini 3.1 Pro Preview and Solar Pro 4 compare?
- Gemini 3.1 Pro Preview takes 1,048,576 tokens; Solar Pro 4 takes 524,288.
- Which ranks higher, Gemini 3.1 Pro Preview or Solar Pro 4?
- Gemini 3.1 Pro Preview ranks higher on the public arena (Gemini 3.1 Pro Preview #9, Solar Pro 4 #177). Ranks move as the leaderboard updates.
- Can I use Gemini 3.1 Pro Preview and Solar Pro 4 with the same API key?
- Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "gemini-3.1-pro-preview" 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 Gemini 3.1 Pro Preview and Solar Pro 4 from the browser chat and the API. No monthly fee.