Model comparison

GPT-5.6 Sol vs GPT-6 Sol

Pricing, context window and real answers (September 2026)

GPT-5.6 Sol (OpenAI) and GPT-6 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 Solopenai logoGPT-6 Sol
ProviderOpenAIOpenAI
Input (per 1M tokens)¥357.4¥357.4
Output (per 1M tokens)¥1,787¥1,787
Typical cost (1,000 in + 500 out tokens × 1,000 calls)¥1,251¥1,251
Context window1,050,000 tokens1,050,000 tokens
Release date7/9/20269/22/2026
Input modalitiesfile, image, textfile, image, text
Throughput (p50)
Arena · overall#18 · ELO 1,483Unranked
Arena · Japanese#5 · ELO 1,503Unranked
Arena · coding#17 · ELO 1,528Unranked

Prices are FastMetal's yen rates before tax. Arena ranks are as of the latest leaderboard scrape.

Which should you pick?

  • Output pricing is identical (¥1,787 per 1M tokens).
  • 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 Sol

“strawberry” can be split into letters: s, t, **r**, a, w, b, e, **r**, **r**, y The letter **r** appears **3 times**.
3.0s78 output tokens

GPT-6 Sol

“Strawberry” is spelled **s-t-r-a-w-b-e-r-r-y**. There’s one **r** near the beginning and two near the end, for a total of **3**.
2.7s76 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 Sol

The error occurs because `users` is `undefined` when `UserList` renders, so JavaScript cannot call `.map()` on it. This often happens when data is loaded asynchronously or the parent does not pass the prop. ### Fix options **1. Give `users` a default value:** ```jsx function UserList({ users = [] }) { return ( <ul> {users.map(user => ( <li key={user.id}>{user.name}</li> ))} </ul> ); } ``` Note that this handles `undefined`, but not an explicitly passed `null`. **2. Handle missing or invalid data explicitly:** ```jsx function UserList({ users }) { if (!Array.isArray(users)) { return <p>No users available.</p>; } return ( <ul> {users.m…
7.1s395 output tokens

GPT-6 Sol

`users` is `undefined` when `UserList` renders, so calling `users.map(...)` throws the error. The component needs an array, but its parent may not be passing `users`, or the data may not have loaded yet. You can default it to an empty array: ```jsx function UserList({ users = [] }) { return ( <ul> {users.map(user => <li key={user.id}>{user.name}</li>)} </ul> ); } ``` Also check the parent component to make sure it passes an array: ```jsx <UserList users={users} /> ``` If `users` comes from an API, initialize its state as `[]` or show a loading state until the data arrives.
2.2s161 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 Sol

### Issues and suggested improvements - Move imports to module scope. - Avoid bare `except:`; it catches programming errors and interrupts such as `KeyboardInterrupt`. - Use `response.raise_for_status()` instead of manually checking only for `200`; other 2xx responses may also be valid. - Retry only transient failures, such as timeouts, connection errors, `429`, and selected `5xx` responses. Retrying most `4xx` errors is not useful. - Use exponential backoff rather than a fixed delay. - Avoid sleeping after the final failed attempt. - Replace `item["active"] == True` with `item.get("active") is True`. - Use a list comprehension for the transformation. - Add type hints and validate arguments…
33.1s1646 output tokens

GPT-6 Sol

The main issues are the bare `except`, which hides errors such as malformed JSON, and retrying every non-200 response, including client errors that usually won’t improve with another attempt. The function also sleeps after its final attempt. ```python import time import requests def get_data(url, retries=3): if retries < 1: raise ValueError("retries must be at least 1") for attempt in range(retries): try: response = requests.get(url, timeout=10) except requests.RequestException: if attempt == retries - 1: raise else: # Retry rate limits and server errors, but not other client errors.…
10.3s814 output tokens

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Frequently asked questions

Which is cheaper, GPT-5.6 Sol or GPT-6 Sol?
Both are ¥1,787 per 1M output tokens on FastMetal (yen, before tax).
How do the context windows of GPT-5.6 Sol and GPT-6 Sol compare?
GPT-5.6 Sol takes 1,050,000 tokens; GPT-6 Sol takes 1,050,000.
Can I use GPT-5.6 Sol and GPT-6 Sol with the same API key?
Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "gpt-5.6-sol" or "gpt-6-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 Sol and GPT-6 Sol from the browser chat and the API. No monthly fee.

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