MiMo-V2.5-Pro vs Solar Mini 4
Pricing, context window and real answers (September 2026)
MiMo-V2.5-Pro (Xiaomi) 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
| MiMo-V2.5-Pro | Solar Mini 4 | |
|---|---|---|
| Provider | Xiaomi | Upstage |
| Input (per 1M tokens) | ¥77.73 | ¥8.94 |
| Output (per 1M tokens) | ¥155.47 | ¥35.74 |
| Typical cost (1,000 in + 500 out tokens × 1,000 calls) | ¥155 | ¥27 |
| Context window | 1,050,000 tokens | 524,288 tokens |
| Release date | 4/22/2026 | 9/23/2026 |
| Input modalities | text | text |
| Throughput (p50) | — | — |
| Arena · overall | #44 · ELO 1,467 | Unranked |
| Arena · Japanese | #52 · ELO 1,426 | Unranked |
| Arena · coding | #25 · ELO 1,521 | 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, 77% less than MiMo-V2.5-Pro.
- For long documents, MiMo-V2.5-Pro: a 1,050,000-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.
MiMo-V2.5-Pro
## Counting the r's in "strawberry"
Let me go through each letter one by one:
| Position | Letter | Is it 'r'? |
|----------|--------|------------|
| 1 | s | No |
| 2 | t | No |
| 3 | **r** | ✅ Yes (#1) |
| 4 | a | No |
| 5 | w | No |
| 6 | b | No |
| 7 | e | No |
| 8 | **r** | ✅ Yes (#2) |
| 9 | **r** | ✅ Yes (#3) |
| 10 | y | No |
**There are 3 r's in "strawberry."**
The word breaks down as **straw·ber·ry**, and the r's appear at the end of "staw" and then twice in the double-r of "rry."
8.3s313 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…
MiMo-V2.5-Pro
# Fixing `Cannot read properties of undefined (reading 'map')`
## The Problem
The error means `users` is `undefined` when the component first renders. This typically happens when:
1. **The parent component hasn't passed the `users` prop**
2. **The data is being fetched asynchronously and isn't available yet**
3. **The prop name is misspelled in the parent**
For example, the parent might be rendering it like this:
```jsx
// ❌ No users prop passed — `users` will be undefined
<UserList />
```
## Solutions
### 1. Add a Default Prop Value (Simple Fix)
```jsx
function UserList({ users = [] }) {
return (
<ul>
{users.map(user => <li key={user.id}>{user.name}</li>)}
</ul>
);
}…
14.4s680 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):…
MiMo-V2.5-Pro
# Code Review: `get_data` Function
## Issues Identified
```
┌──────────────────────────────────────────────────────────────┐
│ ISSUE SEVERITY MAP │
├──────────────────┬────────────┬──────────────────────────────┤
│ Issue │ Severity │ Category │
├──────────────────┼────────────┼──────────────────────────────┤
│ Bare except │ 🔴 High │ Error Handling / Best Prac. │
│ Silent failures │ 🔴 High │ Debuggability │
│ == True check │ 🟡 Medium │ Readability / PEP 8 │
│ Inline imports │ 🟡 Medium │ Best Practice │
│ No type hints │ 🟡 Medium │ Best Practice…
10.4s1572 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, MiMo-V2.5-Pro or Solar Mini 4?
- Per 1M output tokens, MiMo-V2.5-Pro is ¥155.47 and Solar Mini 4 is ¥35.74 on FastMetal (yen, before tax), so Solar Mini 4 is cheaper.
- How do the context windows of MiMo-V2.5-Pro and Solar Mini 4 compare?
- MiMo-V2.5-Pro takes 1,050,000 tokens; Solar Mini 4 takes 524,288.
- Can I use MiMo-V2.5-Pro and Solar Mini 4 with the same API key?
- Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "mimo-v2.5-pro" 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 MiMo-V2.5-Pro and Solar Mini 4 from the browser chat and the API. No monthly fee.