Gemini 3.7 Flash vs GPT-5.6 Luna
Pricing, context window and real answers (August 2026)
Gemini 3.7 Flash (Google) and GPT-5.6 Luna (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 3.7 Flash |  GPT-5.6 Luna | |
|---|---|---|
| Provider | OpenAI | |
| Input (per 1M tokens) | ¥134.03 | ¥35.74 |
| Output (per 1M tokens) | ¥670.13 | ¥214.44 |
| Typical cost (1,000 in + 500 out tokens × 1,000 calls) | ¥469 | ¥143 |
| Context window | 1,048,576 tokens | 1,050,000 tokens |
| Release date | 8/13/2026 | 7/9/2026 |
| Input modalities | text, image, video, file, audio | file, image, text |
| Arena · overall | #9 · ELO 1,490 | #63 · ELO 1,452 |
| Arena · Japanese | Unranked | #36 · ELO 1,444 |
| Arena · coding | #24 · ELO 1,521 | #69 · ELO 1,496 |
Prices are FastMetal's yen rates before tax. Arena ranks are as of the latest leaderboard scrape.
Which should you pick?
- On price, GPT-5.6 Luna: ¥214.44 per 1M output tokens, 68% less than Gemini 3.7 Flash.
- On the Overall arena board, Gemini 3.7 Flash ranks higher (#9; GPT-5.6 Luna is #63).
- On the Coding arena board, Gemini 3.7 Flash ranks higher (#24; GPT-5.6 Luna is #69).
- For long documents, GPT-5.6 Luna: a 1,050,000-token context window against 1,048,576 for Gemini 3.7 Flash.
- 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 3.7 Flash
There are **3** 'r's in the word "strawberry".
### Step-by-step reasoning:
1. **Break down the word into individual letters:**
* 1st letter: **s**
* 2nd letter: **t**
* 3rd letter: **r** *(1st 'r')*
* 4th letter: **a**
* 5th letter: **w**
* 6th letter: **b**
* 7th letter: **e**
* 8th letter: **r** *(2nd 'r')*
* 9th letter: **r** *(3rd 'r')*
* 10th letter: **y**
2. **Identify the positions of 'r':**
* The 3rd letter is an **r** (in "st**r**aw").
* The 8th letter is an **r** (in "be**r**ry").
* The 9th letter is an **r** (in "ber**r**y").
3. **Total count:** 1 + 1 + 1 = **3**.
4.5s530 output tokens
GPT-5.6 Luna
The word **“strawberry”** is spelled:
**s – t – r – a – w – b – e – r – r – y**
The letter **“r”** appears at positions **3, 8, and 9**.
**Answer: 3**
3.0s120 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 3.7 Flash
### Why This Error Happens
This error occurs because the `users` prop is `undefined` when the component renders. Since `map` is an Array method, calling `undefined.map()` causes JavaScript to throw a `TypeError`.
This usually happens when:
1. Data is being fetched asynchronously (e.g., via `fetch` or `axios`), and the component renders **before** the data has arrived.
2. The parent component forgot to pass the `users` prop (`<UserList />`).
3. The initial state in the parent component was initialized as `undefined` (e.g., `const [users, setUsers] = useState()`).
---
### How to Fix It
Here are the best ways to fix it, depending on your use case:
#### Solution 1: Default Parameter (Recom…
9.9s1355 output tokens
GPT-5.6 Luna
`users` is `undefined` when `UserList` renders, so calling `.map()` on it fails. `.map()` only exists on arrays.
Common causes include:
- The parent does not pass a `users` prop.
- The prop name differs, such as `userList` instead of `users`.
- Users are loaded asynchronously and are initially undefined.
- The API response has a different shape, such as `{ data: [...] }`.
### Provide a default value
```jsx
function UserList({ users = [] }) {
return (
<ul>
{users.map(user => (
<li key={user.id}>{user.name}</li>
))}
</ul>
);
}
```
The parent should pass an array:
```jsx
<UserList users={users} />
```
If the list comes from state, initialize it as an empty…
4.8s507 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 3.7 Flash
Here is a detailed review of your function, followed by refactored versions.
---
### Key Issues & Areas for Improvement
1. **Imports inside the function (PEP 8):**
Imports should be placed at the top of the file, not inside a function, to avoid repeated import overhead and improve readability.
2. **Bare `except:` clause (Anti-pattern):**
Catching everything with `except:` intercepts `KeyboardInterrupt`, `SystemExit`, and memory errors, making debugging difficult. Catch specific exceptions like `requests.RequestException` and `ValueError` (for JSON decoding).
3. **Retrying on non-retryable errors:**
A status code like `404 Not Found` or `401 Unauthorized` will never succeed on a…
13.2s2117 output tokens
GPT-5.6 Luna
### Main issues
- Imports should be at module level, not inside the function.
- A bare `except:` catches everything, including programming errors and `KeyboardInterrupt`.
- The function sleeps even after the final failed attempt.
- It retries all HTTP statuses, including permanent errors such as `404`.
- `status_code == 200` excludes other successful `2xx` responses.
- `if item["active"] == True` should generally be `if item.get("active") is True`.
- A `requests.Session` can reuse connections and improve performance.
- Returning `[]` for every failure makes it impossible to distinguish “no active items” from “request failed.”
- Retries should generally use backoff rather than a fixed delay.…
23.3s1978 output tokens
Frequently asked questions
- Which is cheaper, Gemini 3.7 Flash or GPT-5.6 Luna?
- Per 1M output tokens, Gemini 3.7 Flash is ¥670.13 and GPT-5.6 Luna is ¥214.44 on FastMetal (yen, before tax), so GPT-5.6 Luna is cheaper.
- How do the context windows of Gemini 3.7 Flash and GPT-5.6 Luna compare?
- Gemini 3.7 Flash takes 1,048,576 tokens; GPT-5.6 Luna takes 1,050,000.
- Which ranks higher, Gemini 3.7 Flash or GPT-5.6 Luna?
- Gemini 3.7 Flash ranks higher on the public arena (Gemini 3.7 Flash #9, GPT-5.6 Luna #36). Ranks move as the leaderboard updates.
- Can I use Gemini 3.7 Flash and GPT-5.6 Luna with the same API key?
- Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "gemini-3.7-flash" or "gpt-5.6-luna" 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 3.7 Flash and GPT-5.6 Luna from the browser chat and the API. No monthly fee.