FastMetal

Model comparison

GPT-5.6 Terra vs GPT-6.1 Sol

Pricing, context window and real answers (September 2026)

GPT-5.6 Terra (OpenAI) and GPT-6.1 Sol (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

openai logoGPT-5.6 Terraopenai logoGPT-6.1 Sol
ProviderOpenAIOpenAI
Input (per 1M tokens)¥357.4¥357.4
Output (per 1M tokens)¥2,144.4¥1,787
Typical cost (1,000 in + 500 out tokens × 1,000 calls)¥1,430¥1,251
Context window1,050,000 tokens1,050,000 tokens
Release date7/9/20269/29/2026
Input modalitiesfile, image, textfile, image, text
Throughput (p50)179 tokens/s (n=17)—
Arena · overall#50 · ELO 1,465Unranked
Arena · Japanese#25 · ELO 1,466Unranked
Arena · coding#40 · ELO 1,516Unranked

Prices are FastMetal's yen rates before tax.

Rankings: LMArena leaderboard dataset (lmarena-ai/leaderboard-dataset), CC BY 4.0, snapshot 2026-09-25; category names mapped and ratings rounded by FastMetal.

Which should you pick?

  • On price, GPT-6.1 Sol: ¥1,787 per 1M output tokens, 17% less than GPT-5.6 Terra.
  • 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 Terra

“strawberry” is spelled: s t **r** a w b e **r** **r** y There are **3** occurrences of the letter **r**.
3.6s71 output tokens

GPT-6.1 Sol

“strawberry” is spelled **s-t-r-a-w-b-e-r-r-y**. The letter **r** appears at positions **3, 8, and 9**. So, there are **3 r’s** in “strawberry.”
2.8s88 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 Terra

The error means `users` is `undefined` when `UserList` renders, so React tries to evaluate: ```js users.map(...) ``` But `.map()` only exists on arrays. Common causes: - The parent component does not pass a `users` prop. - The user data is loaded asynchronously and has not arrived on the first render. - The API response shape differs from what you expect, e.g. data is in `response.data.users` rather than `response.data`. - The parent initializes its user state as `undefined` or `null`. ## Fix options ### 1. Initialize users as an empty array In the parent component: ```jsx const [users, setUsers] = useState([]); ``` Then pass it normally: ```jsx <UserList users={users} /> ``` An e…
5.8s559 output tokens

GPT-6.1 Sol

The error means **`users` is `undefined` when `UserList` renders**. Calling `.map()` on `undefined` throws this error. This commonly happens when the parent doesn’t pass the `users` prop, or when data hasn’t finished loading yet. ### Fix: provide a default empty array ```jsx function UserList({ users = [] }) { return ( <ul> {users.map(user => ( <li key={user.id}>{user.name}</li> ))} </ul> ); } ``` This renders an empty list if `users` is omitted or `undefined`. It does **not** handle `null`. ### Check the parent component too Make sure it passes an array: ```jsx <UserList users={users} /> ``` If you’re fetching users asynchronously, initialize the stat…
5.8s306 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 Terra

Here are the main areas to improve: ### Issues in the original code - **Imports inside the function**: Move `requests` and `time` imports to module scope. - **Bare `except:`**: This catches everything, including `KeyboardInterrupt` and programming errors. Catch `requests.RequestException` (and possibly JSON decoding errors) instead. - **Status code check**: Prefer `response.raise_for_status()` or `response.ok` over manually checking only for `200`. Successful responses can include other 2xx status codes. - **`== True`**: Use `if item.get("active"):` instead. - **Potential `KeyError`**: `item["name"]`, `item["id"]`, and `item["active"]` can fail if the API response is incomplete. Use `.get(…
10.6s939 output tokens

GPT-6.1 Sol

The function is short, but its main weakness is that it hides failures: a network error, invalid JSON, and a genuinely empty result all return `[]`. ### Suggested improvements - **Move imports to module scope.** This is conventional and makes dependencies visible. Repeated imports are cached, so the performance benefit is minor. - **Avoid bare `except:`.** It catches everything, including `KeyboardInterrupt` and `SystemExit`, and can hide programming errors. - **Handle HTTP errors explicitly.** `raise_for_status()` provides useful exceptions. Retry transient failures such as timeouts, connection errors, HTTP 429, and HTTP 5xx—not permanent errors such as HTTP 404. - **Don’t sleep after the…
19.0s1094 output tokens

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Frequently asked questions

Which is cheaper, GPT-5.6 Terra or GPT-6.1 Sol?
Per 1M output tokens, GPT-5.6 Terra is ¥2,144.4 and GPT-6.1 Sol is ¥1,787 on FastMetal (yen, before tax), so GPT-6.1 Sol is cheaper.
How do the context windows of GPT-5.6 Terra and GPT-6.1 Sol compare?
GPT-5.6 Terra takes 1,050,000 tokens; GPT-6.1 Sol takes 1,050,000.
Can I use GPT-5.6 Terra and GPT-6.1 Sol with the same API key?
Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "gpt-5.6-terra" or "gpt-6.1-sol" 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 Terra and GPT-6.1 Sol from the browser chat and the API. No monthly fee.

Create a free accountTry GPT-5.6 Terra in chatTry GPT-6.1 Sol in chat

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