Gemini 3.5 Flash vs Grok 4.6
Pricing, context window and real answers (August 2026)
Gemini 3.5 Flash (Google) and Grok 4.6 (xAI), 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 |  Grok 4.6 | |
|---|---|---|
| Provider | xAI | |
| Input (per 1M tokens) | ¥268.05 | ¥357.4 |
| Output (per 1M tokens) | ¥1,608.3 | ¥1,072.2 |
| Typical cost (1,000 in + 500 out tokens × 1,000 calls) | ¥1,072 | ¥894 |
| Context window | 1,048,576 tokens | 500,000 tokens |
| Release date | 5/19/2026 | 8/12/2026 |
| Input modalities | text, image, video, file, audio | text, image, file |
| Arena · overall | #18 · ELO 1,476 | Unranked |
| Arena · Japanese | #20 · ELO 1,456 | Unranked |
| Arena · coding | #45 · ELO 1,507 | Unranked |
Prices are FastMetal's yen rates before tax. Arena ranks are as of the latest leaderboard scrape.
Which should you pick?
- On price, Grok 4.6: ¥1,072.2 per 1M output tokens, 33% less than Gemini 3.5 Flash.
- For long documents, Gemini 3.5 Flash: a 1,048,576-token context window against 500,000 for Grok 4.6.
- 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
Grok 4.6
The word "strawberry" consists of the following letters in order:
s-t-r-a-w-b-e-r-r-y
Checking each one:
- s: not r
- t: not r
- r: yes (count = 1)
- a: not r
- w: not r
- b: not r
- e: not r
- r: yes (count = 2)
- r: yes (count = 3)
- y: not r
There are exactly 3 r's.
Final answer: 3
3.9s451 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
Grok 4.6
**The error happens because `users` is `undefined` when `.map()` is called.**
`UserList` destructures `{ users }` from its props. If the parent doesn't pass a `users` prop (or passes `undefined`/`null`), `users` is `undefined` and `undefined.map` throws.
This is extremely common when:
- Data is loaded asynchronously (initial render happens before the fetch finishes).
- The parent component forgets to pass the prop or uses a different name.
- The component is rendered before the data is ready (e.g. in a loading state).
### Quick fixes
**1. Default to an empty array (recommended)**
```jsx
function UserList({ users = [] }) {
return (
<ul>
{users.map(user => (
<li key={us…
20.3s598 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
Grok 4.6
Here is a focused review of the function, followed by a cleaned-up version.
## Issues
**Imports inside the function**
`requests` and `time` should live at module level. Importing on every call is slower, hides dependencies, and is harder to mock in tests.
**Bare `except:`**
This swallows `KeyboardInterrupt`, `SystemExit`, and programming errors. Catch `requests.RequestException` (network/timeout/HTTP adapter errors) and JSON/`KeyError`/`TypeError` separately.
**Retrying the wrong things**
A 404 or 400 will never succeed on retry. Retry transient failures (timeouts, connection errors, 429, 5xx). Fail fast on most 4xx responses.
**Sleep after the last attempt**
On the final failur…
27.9s1770 output tokens
Frequently asked questions
- Which is cheaper, Gemini 3.5 Flash or Grok 4.6?
- Per 1M output tokens, Gemini 3.5 Flash is ¥1,608.3 and Grok 4.6 is ¥1,072.2 on FastMetal (yen, before tax), so Grok 4.6 is cheaper.
- How do the context windows of Gemini 3.5 Flash and Grok 4.6 compare?
- Gemini 3.5 Flash takes 1,048,576 tokens; Grok 4.6 takes 500,000.
- Can I use Gemini 3.5 Flash and Grok 4.6 with the same API key?
- Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "gemini-3.5-flash" or "grok-4.6" 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 Grok 4.6 from the browser chat and the API. No monthly fee.