FastMetal

Model comparison

GPT-5.4 Nano vs GPT-6.1 Sol

Pricing, context window and real answers (September 2026)

GPT-5.4 Nano (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-5.4 Nanoopenai logoGPT-6.1 Sol
ProviderOpenAIOpenAI
Input (per 1M tokens)¥35.74¥357.4
Output (per 1M tokens)¥223.38¥1,787
Typical cost (1,000 in + 500 out tokens × 1,000 calls)¥147¥1,251
Context window400,000 tokens1,050,000 tokens
Release date3/17/20269/29/2026
Input modalitiesfile, image, textfile, image, text
Throughput (p50)——
Arena · overall#155 · ELO 1,401Unranked
Arena · Japanese#104 · ELO 1,373Unranked
Arena · coding#134 · ELO 1,460Unranked

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-5.4 Nano: ¥223.38 per 1M output tokens, 87% less than GPT-6.1 Sol.
  • For long documents, GPT-6.1 Sol: a 1,050,000-token context window against 400,000 for GPT-5.4 Nano.
  • 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-5.4 Nano

**Step 1:** Write the word: **strawberry** **Step 2:** Count each letter **r** in the word: - s **t r** a w b e **r r** y There are **3** **r**’s in total (**one** after the **t**, and **two** near the end). ✅ **Answer: 3**
1.5s86 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-5.4 Nano

This error means that **`users` is `undefined` (or otherwise not an array)** when your component renders, so calling `users.map(...)` throws: ```js users.map(...) ^^^^ reading 'map' of undefined ``` ### Why it happens Common causes: - You render `<UserList />` before data has loaded (e.g., `users` comes from an async fetch). - The parent component passes the wrong prop name (e.g., `user` instead of `users`). - The API/parent state initializes `users` as `undefined` rather than `[]`. - You’re destructuring a prop incorrectly upstream. ### Fix options #### 1) Ensure `users` is always an array (recommended) Initialize/default it in the component: ```js function UserList({ users = []…
3.3s383 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-5.4 Nano

Here are key improvements (readability, performance, robustness, best practices) and a revised version of your function. ## What to improve 1. **Avoid bare `except:`** Catch specific exceptions from `requests` (e.g., `requests.exceptions.RequestException`) to avoid hiding bugs. 2. **Prefer `raise_for_status()` or check status codes clearly** `r.raise_for_status()` is a common pattern. 3. **Use exponential backoff (or at least a clear retry delay)** Instead of sleeping the same amount every time, consider increasing delay. 4. **Reuse a `requests.Session()` (optional but best practice)** If this function is called repeatedly, passing a session or creating one outside i…
4.4s718 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-5.4 Nano or GPT-6.1 Sol?
Per 1M output tokens, GPT-5.4 Nano is ¥223.38 and GPT-6.1 Sol is ¥1,787 on FastMetal (yen, before tax), so GPT-5.4 Nano is cheaper.
How do the context windows of GPT-5.4 Nano and GPT-6.1 Sol compare?
GPT-5.4 Nano takes 400,000 tokens; GPT-6.1 Sol takes 1,050,000.
Can I use GPT-5.4 Nano and GPT-6.1 Sol with the same API key?
Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "gpt-5.4-nano" 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-5.4 Nano and GPT-6.1 Sol from the browser chat and the API. No monthly fee.

Create a free accountTry GPT-5.4 Nano in chatTry GPT-6.1 Sol in chat

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