Model comparison

GPT-5.6 Sol vs LLM-jp-3.1 8x13B instruct4

Pricing, context window and real answers (August 2026)

GPT-5.6 Sol (OpenAI) and LLM-jp-3.1 8x13B instruct4 (Llm Jp), 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 SolLLM-jp-3.1 8x13B instruct4
ProviderOpenAILlm Jp
Input (per 1M tokens)¥893.5¥16
Output (per 1M tokens)¥5,361¥79
Typical cost (1,000 in + 500 out tokens × 1,000 calls)¥3,574¥56
Context window1,050,000 tokens4,096 tokens
Release date7/9/20263/21/2026
Input modalitiesfile, image, texttext
Arena · overall#17 · ELO 1,482Unranked
Arena · Japanese#1 · ELO 1,529Unranked
Arena · coding#15 · ELO 1,528Unranked

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

Which should you pick?

  • On price, LLM-jp-3.1 8x13B instruct4: ¥79 per 1M output tokens, 99% less than GPT-5.6 Sol.
  • For long documents, GPT-5.6 Sol: a 1,050,000-token context window against 4,096 for LLM-jp-3.1 8x13B instruct4.
  • 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

LLM-jp-3.1 8x13B instruct4

To count the number of 'r's in the word 'strawberry', follow these steps: 1. Identify the word: The word we are examining is 'strawberry'. 2. Understand the task: We need to find and count all occurrences of the letter 'r' in this word. 3. Begin with the first letter: The first letter is 's', which is not 'r', so we move on to the next letter. 4. Proceed to the second letter: The second letter is 't', which is also not 'r', so we continue to the third letter. 5. Reach the third letter: The third letter is 'r'. We have found one 'r'. 6. Continue to the fourth letter: The fourth letter is 'a', which is not 'r', so we move on to the fifth letter. 7. Examine the fifth letter: The fifth letter i…
4.0s400 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

LLM-jp-3.1 8x13B instruct4

The error TypeError: Cannot read properties of undefined (reading 'map') suggests that the 'users' argument passed to the UserList component is undefined or does not have a 'map' method. The cause of the problem may be that the users variable is not being passed correctly or is not defined in the parent component. Check the props being passed to the UserList component to ensure that they are defined and contain the expected data. To fix the issue, you can add some error handling and debugging to your component. Try logging the users variable to the console to verify that it is not undefined: ```jsx function UserList({ users }) { console.log("Users:", users); if (!users) { return <…
3.0s279 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

LLM-jp-3.1 8x13B instruct4

The provided Python function aims to get data from a URL using the requests library, filter out specific items based on their "active" field, and return the result. Here are some suggestions to improve readability, performance, and adherence to best practices: 1. Configure the linter (e.g., flake8 or pylint) to ensure code quality and enforce a consistent coding style. 2. Use type hints to improve readability and maintainability. 3. Use context managers (with statement) for handling requests: 4. Rewrite the function using a more functional programming style: Here's the improved version of the function: ```python import requests import time from typing import List, Dict, Any def get_da…
3.9s406 output tokens

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Frequently asked questions

Which is cheaper, GPT-5.6 Sol or LLM-jp-3.1 8x13B instruct4?
Per 1M output tokens, GPT-5.6 Sol is ¥5,361 and LLM-jp-3.1 8x13B instruct4 is ¥79 on FastMetal (yen, before tax), so LLM-jp-3.1 8x13B instruct4 is cheaper.
How do the context windows of GPT-5.6 Sol and LLM-jp-3.1 8x13B instruct4 compare?
GPT-5.6 Sol takes 1,050,000 tokens; LLM-jp-3.1 8x13B instruct4 takes 4,096.
Can I use GPT-5.6 Sol and LLM-jp-3.1 8x13B instruct4 with the same API key?
Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "gpt-5.6-sol" or "llm-jp-3.1-8x13b-instruct4" 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 LLM-jp-3.1 8x13B instruct4 from the browser chat and the API. No monthly fee.

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