FastMetal

Model comparison

GPT-5.6 Luna vs MiniMax M3.1 Flash

Pricing, context window and real answers (October 2026)

GPT-5.6 Luna (OpenAI) and MiniMax M3.1 Flash (MiniMax), 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

openai logoGPT-5.6 Lunaminimax logoMiniMax M3.1 Flash
ProviderOpenAIMiniMax
Input (per 1M tokens)$0.211$0.1583
Output (per 1M tokens)$1.27$0.633
Typical cost (1,000 in + 500 out tokens × 1,000 calls)$0.844$0.4748
Context window1,050,000 tokens1,048,576 tokens
Release date7/9/202610/19/2026
Input modalitiesfile, image, texttext, image
Throughput (p50)185 tokens/s (n=26)—
Arena · overall#75 · ELO 1,453Unranked
Arena · Japanese#55 · ELO 1,431Unranked
Arena · coding#75 · ELO 1,501Unranked

Prices are FastMetal's rates, before tax.

Rankings: LMArena leaderboard dataset (lmarena-ai/leaderboard-dataset), CC BY 4.0, snapshot 2026-10-15; category names mapped and ratings rounded by FastMetal.

Which should you pick?

  • On price, MiniMax M3.1 Flash: $0.633 per 1M output tokens, 50% less than GPT-5.6 Luna.
  • For long documents, GPT-5.6 Luna: a 1,050,000-token context window against 1,048,576 for MiniMax M3.1 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.

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

MiniMax M3.1 Flash

1. Spell **strawberry**: **s – t – r – a – w – b – e – r – r – y** 2. Count the letter **r**: it appears at positions **3, 8, and 9**. **Total: 3 “r”s.**
3.0s193 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-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

MiniMax M3.1 Flash

The error occurs because `users` is `undefined` when `UserList` renders. Calling `.map()` on `undefined` causes the `TypeError`. This commonly happens when: - `<UserList />` is rendered without passing the `users` prop. - The prop has a different name, such as `user`. - Data is still loading and the parent initializes its state as `undefined`. - An API response is accessed before it exists. ### Immediate fix Provide a default empty array: ```jsx function UserList({ users = [] }) { return ( <ul> {users.map(user => ( <li key={user.id}>{user.name}</li> ))} </ul> ); } ``` Then pass the actual data from the parent: ```jsx const [users, setUsers] = useState([…
7.3s744 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-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

MiniMax M3.1 Flash

The function is understandable, but it has a few important issues: - `except:` catches programming errors such as `KeyError`, `TypeError`, and even `KeyboardInterrupt`. - Every non-200 response is retried, including permanent failures such as 400, 401, and 404. - It sleeps after the final failed attempt. - Returning `[]` makes a failed request indistinguishable from a successful response containing no active records. - A fixed delay can cause clients to retry simultaneously; exponential backoff and `Retry-After` are preferable. - `item["active"] == True` should be `item.get("active") is True` if the API contract says it is a JSON boolean. - A `Session` can reuse connections, while `requests…
146.5s

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Frequently asked questions

Which is cheaper, GPT-5.6 Luna or MiniMax M3.1 Flash?
Per 1M output tokens, GPT-5.6 Luna is $1.27 and MiniMax M3.1 Flash is $0.633 on FastMetal (US dollars, before tax), so MiniMax M3.1 Flash is cheaper.
How do the context windows of GPT-5.6 Luna and MiniMax M3.1 Flash compare?
GPT-5.6 Luna takes 1,050,000 tokens; MiniMax M3.1 Flash takes 1,048,576.
Can I use GPT-5.6 Luna and MiniMax M3.1 Flash with the same API key?
Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "gpt-5.6-luna" or "minimax-m3.1-flash" 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-5.6 Luna and MiniMax M3.1 Flash from the browser chat and the API. No monthly fee.

Create a free accountTry GPT-5.6 Luna in chatTry MiniMax M3.1 Flash in chat

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