Gemini 3.5 Flash vs GPT-4o-mini
Pricing, context window and real answers (September 2026)
Gemini 3.5 Flash (Google) and GPT-4o-mini (OpenAI), 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 3.5 Flash |  GPT-4o-mini | |
|---|---|---|
| Provider | OpenAI | |
| Input (per 1M tokens) | ¥268.05 | ¥26.81 |
| Output (per 1M tokens) | ¥1,608.3 | ¥107.22 |
| Typical cost (1,000 in + 500 out tokens × 1,000 calls) | ¥1,072 | ¥80 |
| Context window | 1,048,576 tokens | 128,000 tokens |
| Release date | 5/19/2026 | 7/18/2024 |
| Input modalities | text, image, video, file, audio | text, image, file |
| Throughput (p50) | — | — |
| Arena · overall | #25 · ELO 1,478 | #251 · ELO 1,318 |
| Arena · Japanese | #19 · ELO 1,468 | #187 · ELO 1,250 |
| Arena · coding | #55 · ELO 1,506 | #259 · ELO 1,348 |
Prices are FastMetal's yen rates before tax. Arena ranks are as of the latest leaderboard scrape.
Which should you pick?
- On price, GPT-4o-mini: ¥107.22 per 1M output tokens, 93% less than Gemini 3.5 Flash.
- On the Overall arena board, Gemini 3.5 Flash ranks higher (#25; GPT-4o-mini is #251).
- On the Japanese arena board, Gemini 3.5 Flash ranks higher (#19; GPT-4o-mini is #187).
- On the Coding arena board, Gemini 3.5 Flash ranks higher (#55; GPT-4o-mini is #259).
- For long documents, Gemini 3.5 Flash: a 1,048,576-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.
Gemini 3.5 Flash
There are **3** 'r's in the word "strawberry".
Here is the step-by-step breakdown of how to count them:
1. **Break the word down into its individual letters:**
* 1st letter: **s**
* 2nd letter: **t**
* 3rd letter: **r** (First 'r')
* 4th letter: **a**
* 5th letter: **w**
* 6th letter: **b**
* 7th letter: **e**
* 8th letter: **r** (Second 'r')
* 9th letter: **r** (Third 'r')
* 10th letter: **y**
2. **Identify and count only the 'r's:**
* s - t - **r** (1) - a - w - b - e - **r** (2) - **r** (3) - y
By counting them as we go through the word, we find a total of **3** 'r's.
4.8s601 output tokens
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
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 3.5 Flash
### What is causing this error?
The error `TypeError: Cannot read properties of undefined (reading 'map')` means that your `UserList` component is trying to call `.map()` on the `users` variable, but **`users` is currently `undefined`**.
This usually happens for one of two reasons:
1. **The parent component forgot to pass the prop:** `<UserList />` was rendered without the `users` attribute.
2. **Asynchronous data fetching:** The parent component fetches the users from an API, but the API request hasn't finished yet when the component first renders, so `users` starts as `undefined`.
---
### How to fix it
Here are the three best ways to fix this, depending on how you want your UI to beh…
11.2s1524 output tokens
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
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 3.5 Flash
Here is a review of your function, followed by two improved versions (one that keeps your structure but makes it Pythonic, and one production-ready version that uses industry best practices).
---
### Key Areas for Improvement
1. **Imports inside the function:** `import requests` and `import time` should be at the top of the file (PEP 8). Keeping them inside the function slows down execution if the function is called repeatedly.
2. **Bare `except:` clause:** Using `except:` without specifying an exception type is a major anti-pattern. It catches things you don't want to catch, like `KeyboardInterrupt` (Ctrl+C) or `SystemExit`. It should target `requests.RequestException`.
3. **Implicit `Tr…
19.7s2975 output tokens
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
Frequently asked questions
- Which is cheaper, Gemini 3.5 Flash or GPT-4o-mini?
- Per 1M output tokens, Gemini 3.5 Flash is ¥1,608.3 and GPT-4o-mini is ¥107.22 on FastMetal (yen, before tax), so GPT-4o-mini is cheaper.
- How do the context windows of Gemini 3.5 Flash and GPT-4o-mini compare?
- Gemini 3.5 Flash takes 1,048,576 tokens; GPT-4o-mini takes 128,000.
- Which ranks higher, Gemini 3.5 Flash or GPT-4o-mini?
- Gemini 3.5 Flash ranks higher on the public arena (Gemini 3.5 Flash #19, GPT-4o-mini #187). Ranks move as the leaderboard updates.
- Can I use Gemini 3.5 Flash and GPT-4o-mini with the same API key?
- Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "gemini-3.5-flash" or "gpt-4o-mini" 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 3.5 Flash and GPT-4o-mini from the browser chat and the API. No monthly fee.