GPT-4.1 Nano vs Solar Pro 4
Pricing, context window and real answers (September 2026)
GPT-4.1 Nano (OpenAI) 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
 GPT-4.1 Nano | Solar Pro 4 | |
|---|---|---|
| Provider | OpenAI | Upstage |
| Input (per 1M tokens) | ¥17.87 | ¥16.08 |
| Output (per 1M tokens) | ¥71.48 | ¥64.33 |
| Typical cost (1,000 in + 500 out tokens × 1,000 calls) | ¥54 | ¥48 |
| Context window | 1,047,576 tokens | 524,288 tokens |
| Release date | 4/14/2025 | 8/10/2026 |
| Input modalities | image, text, file | text |
| Throughput (p50) | — | — |
| Arena · overall | #243 · ELO 1,322 | #177 · ELO 1,376 |
| Arena · Japanese | #195 · ELO 1,234 | Unranked |
| Arena · coding | #226 · ELO 1,374 | #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, 10% less than GPT-4.1 Nano.
- On the Overall arena board, Solar Pro 4 ranks higher (#177; GPT-4.1 Nano is #243).
- On the Coding arena board, Solar Pro 4 ranks higher (#144; GPT-4.1 Nano is #226).
- For long documents, GPT-4.1 Nano: a 1,047,576-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.
GPT-4.1 Nano
Let's analyze the word "strawberry" step by step to count the number of 'r's.
1. Write down the word: **strawberry**
2. Examine each letter one by one:
- s: no
- t: no
- r: yes (first 'r')
- a: no
- w: no
- b: no
- e: no
- r: yes (second 'r')
- r: yes (third 'r')
- y: no
3. Counting the 'r's found:
- First 'r' (at position 3)
- Second 'r' (at position 8)
- Third 'r' (at position 9)
So, there are **3** 'r's in "strawberry."
**Final answer: 3**
2.0s183 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…
GPT-4.1 Nano
The error:
```
TypeError: Cannot read properties of undefined (reading 'map')
```
indicates that `users` is `undefined` at the time your `UserList` component is rendering, and you're trying to call `map` on it.
### Why is this happening?
In React, if a prop (`users` in this case) is not provided or is undefined, trying to do `users.map(...)` causes this error. This can happen if:
- The parent component does not pass `users`.
- `users` might be `null` or `undefined` initially, especially if data fetching is involved.
### How to fix it
**Option 1: Provide a default value for `users`**
Ensure that `users` defaults to an empty array if it is not provided:
```jsx
function UserList({ users…
4.3s514 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):…
GPT-4.1 Nano
Here's a review and an improved version of your function:
### Key improvements:
1. **Move imports to the top**: Imports should generally be at the top of the file, not inside functions.
2. **Specify exception types**: Catch specific exceptions rather than a generic `except`.
3. **Use context managers if needed**: Not necessary here, but good to consider.
4. **Avoid repeated code**: The sleep statement is the same whether there is a request exception or a non-200 status.
5. **Simplify filtering**: Use list comprehensions for clarity.
6. **Improve variable names**: For readability.
7. **Add optional headers or parameters** if needed (not required here).
8. **Optional:** Add more descriptive e…
3.4s391 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, GPT-4.1 Nano or Solar Pro 4?
- Per 1M output tokens, GPT-4.1 Nano is ¥71.48 and Solar Pro 4 is ¥64.33 on FastMetal (yen, before tax), so Solar Pro 4 is cheaper.
- How do the context windows of GPT-4.1 Nano and Solar Pro 4 compare?
- GPT-4.1 Nano takes 1,047,576 tokens; Solar Pro 4 takes 524,288.
- Which ranks higher, GPT-4.1 Nano or Solar Pro 4?
- Solar Pro 4 ranks higher on the public arena (GPT-4.1 Nano #195, Solar Pro 4 #177). Ranks move as the leaderboard updates.
- Can I use GPT-4.1 Nano and Solar Pro 4 with the same API key?
- Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "gpt-4.1-nano" 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 GPT-4.1 Nano and Solar Pro 4 from the browser chat and the API. No monthly fee.