Gemini 3.8 Flash vs GPT-5 Mini
Pricing, context window and real answers (September 2026)
Gemini 3.8 Flash (Google) and GPT-5 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 3.8 Flash |  GPT-5 Mini | |
|---|---|---|
| Provider | OpenAI | |
| Input (per 1M tokens) | ¥134.03 | ¥44.68 |
| Output (per 1M tokens) | ¥670.13 | ¥357.4 |
| Typical cost (1,000 in + 500 out tokens × 1,000 calls) | ¥469 | ¥223 |
| Context window | 1,048,576 tokens | 400,000 tokens |
| Release date | 9/2/2026 | 8/7/2025 |
| Input modalities | text, image, video, file, audio | text, image, file |
| Throughput (p50) | — | — |
| Arena · overall | #9 · ELO 1,493 | #163 · ELO 1,390 |
| Arena · Japanese | Unranked | #109 · ELO 1,365 |
| Arena · coding | #10 · ELO 1,535 | #172 · ELO 1,431 |
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 Mini: ¥357.4 per 1M output tokens, 47% less than Gemini 3.8 Flash.
- On the Overall arena board, Gemini 3.8 Flash ranks higher (#9; GPT-5 Mini is #163).
- On the Coding arena board, Gemini 3.8 Flash ranks higher (#10; GPT-5 Mini is #172).
- For long documents, Gemini 3.8 Flash: a 1,048,576-token context window against 400,000 for GPT-5 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 3.8 Flash
There are **3** 'r's in the word "strawberry".
Here is the step-by-step breakdown:
1. **Break the word into its individual letters:**
* **s** (1st letter)
* **t** (2nd letter)
* **r** (3rd letter) — **1st 'r'**
* **a** (4th letter)
* **w** (5th letter)
* **b** (6th letter)
* **e** (7th letter)
* **r** (8th letter) — **2nd 'r'**
* **r** (9th letter) — **3rd 'r'**
* **y** (10th letter)
2. **Count the occurrences:**
* One 'r' is in the first syllable: "st**r**aw"
* Two 'r's are in the second syllable: "be**rr**y"
Total: **3**
3.9s562 output tokens
GPT-5 Mini
We examine the word "strawberry" letter by letter:
1. s — not an r (count = 0)
2. t — not an r (count = 0)
3. r — an r (count = 1)
4. a — not an r (count = 1)
5. w — not an r (count = 1)
6. b — not an r (count = 1)
7. e — not an r (count = 1)
8. r — an r (count = 2)
9. r — an r (count = 3)
10. y — not an r (count = 3)
Total number of 'r's = 3.
5.2s382 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 3.8 Flash
### The Cause
This error occurs because the `users` prop is `undefined` when the component renders, and JavaScript cannot call `.map()` on `undefined`.
This typically happens in two common scenarios:
1. **Asynchronous data fetching:** The parent component fetches `users` from an API. On the initial render, the data hasn't arrived yet, so `users` defaults to `undefined`.
2. **Missing prop:** The parent component forgot to pass `users` (e.g., `<UserList />` instead of `<UserList users={data} />`).
---
### How to Fix It
Here are the most common ways to resolve this:
#### Option 1: Provide a default parameter (Recommended)
Set a default value of an empty array (`[]`) for `users`. If `users…
7.1s1003 output tokens
GPT-5 Mini
That error means users is undefined when you call users.map(...). map is an Array method, so calling it on undefined throws "Cannot read properties of undefined (reading 'map')".
Common causes
- The parent component didn't pass a users prop.
- users is still loading (e.g. fetched asynchronously) and is null/undefined until the fetch completes.
- The parent initialized users to null instead of an empty array.
How to fix
Choose one or more of these approaches depending on your app:
1) Initialize the parent state as an array
If users is state in the parent, initialize it to [] so the child always receives an array:
const [users, setUsers] = useState([]);
// fetch and setUsers(data)
2) Give…
8.0s966 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 3.8 Flash
Here is a code review of your function, broken down by issue category, followed by refactored versions.
---
### Key Issues & Areas for Improvement
#### 1. Correctness & Error Handling
* **Bare `except:` clause:** Catching all exceptions with a bare `except:` is dangerous. It suppresses system exits (`KeyboardInterrupt`, `SystemExit`) and masks programming bugs (like `KeyError` or `NameError`). You should catch specific exceptions, primarily `requests.RequestException`.
* **Silent failure returning `[]`:** If all retries fail, returning an empty list makes it impossible for the caller to distinguish between *"the API returned 0 active items"* and *"the network is completely down"*. It is u…
15.1s2139 output tokens
GPT-5 Mini
Thanks — this is a nice simple function, but it can be improved in several ways: move imports to module scope, avoid broad except:, use connection pooling (Session) for performance, use specific exception types, add logging and docstring, avoid comparing to True, use list comprehensions, validate JSON shape, and implement backoff (or use urllib3 Retry).
Below are two improved alternatives and a short rationale for the changes.
1) A simple, clear improvement (small changes, explicit errors, backoff + jitter)
- Moves imports to top-level
- Uses requests.Session for connection pooling
- Catches specific exceptions (requests.RequestException, ValueError)
- Uses list comprehension and item.get(…
13.6s1702 output tokens
Frequently asked questions
- Which is cheaper, Gemini 3.8 Flash or GPT-5 Mini?
- Per 1M output tokens, Gemini 3.8 Flash is ¥670.13 and GPT-5 Mini is ¥357.4 on FastMetal (yen, before tax), so GPT-5 Mini is cheaper.
- How do the context windows of Gemini 3.8 Flash and GPT-5 Mini compare?
- Gemini 3.8 Flash takes 1,048,576 tokens; GPT-5 Mini takes 400,000.
- Which ranks higher, Gemini 3.8 Flash or GPT-5 Mini?
- Gemini 3.8 Flash ranks higher on the public arena (Gemini 3.8 Flash #9, GPT-5 Mini #109). Ranks move as the leaderboard updates.
- Can I use Gemini 3.8 Flash and GPT-5 Mini with the same API key?
- Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "gemini-3.8-flash" or "gpt-5-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 3.8 Flash and GPT-5 Mini from the browser chat and the API. No monthly fee.