Claude Haiku 5.5 vs GPT-5.6 Sol
Pricing, context window and real answers (October 2026)
Claude Haiku 5.5 (Anthropic) and GPT-5.6 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
 Claude Haiku 5.5 |  GPT-5.6 Sol | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Input (per 1M tokens) | $0.1055 | $2.20 |
| Output (per 1M tokens) | $0.5275 | $11.00 |
| Typical cost (1,000 in + 500 out tokens × 1,000 calls) | $0.3693 | $7.70 |
| Context window | 1,000,000 tokens | 1,050,000 tokens |
| Release date | 10/7/2026 | 7/9/2026 |
| Input modalities | text, image, file | file, image, text |
| Throughput (p50) | — | 220 tokens/s (n=25) |
| Arena · overall | Unranked | #20 · ELO 1,484 |
| Arena · Japanese | Unranked | #13 · ELO 1,495 |
| Arena · coding | Unranked | #14 · ELO 1,534 |
Prices are FastMetal's rates, before tax.
Rankings: LMArena leaderboard dataset (lmarena-ai/leaderboard-dataset), CC BY 4.0, snapshot 2026-10-02; category names mapped and ratings rounded by FastMetal.
Which should you pick?
- On price, Claude Haiku 5.5: $0.5275 per 1M output tokens, 95% less than GPT-5.6 Sol.
- For long documents, GPT-5.6 Sol: a 1,050,000-token context window against 1,000,000 for Claude Haiku 5.5.
- 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.
Claude Haiku 5.5
There are **3** r's in "strawberry."
1. **Spell out the word:** s, t, r, a, w, b, e, r, r, y
2. **Go through each letter and count the r's:**
- Position 3: **r** (count = 1)
- Position 8: **r** (count = 2)
- Position 9: **r** (count = 3)
3. **Check the rest:** s, t, a, w, b, e, and y are not r's.
Total: **3**
2.4s200 output tokens
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
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…
Claude Haiku 5.5
The error means `users` is `undefined` when `UserList` renders, so `.map` is called on nothing. The component destructures the `users` prop, but the parent didn't pass it, or passed `undefined`.
## Common causes
**1. The parent doesn't pass the prop, or uses a different name**
```jsx
<UserList /> // users is undefined
<UserList user={users} /> // wrong name: "user" instead of "users"
```
**2. The data hasn't loaded yet (most common with fetched data)**
```jsx
function App() {
const [users, setUsers] = useState(); // undefined initially
useEffect(() => {
fetch('/api/users').then(r => r.json()).then(setUsers);
}, []);
return <UserList users={users} />;…
5.1s888 output tokens
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
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):…
Claude Haiku 5.5
## Issues
**Correctness and robustness**
1. **Bare `except:`** catches everything, including `KeyboardInterrupt` and `SystemExit`, so Ctrl+C may not stop the program. Catch specific exceptions: `requests.RequestException` for network problems and `ValueError` for invalid JSON.
2. **Retries non-retryable errors.** A 404 or 401 won't succeed on retry, so retrying wastes time. Only retry transient failures such as 429, 5xx, timeouts, and connection errors.
3. **Sleeps after the final attempt.** The loop sleeps even when no retry follows.
4. **Fixed sleep with no backoff.** Exponential backoff is the standard approach for retries.
5. **Silent failure.** Every failure returns `[]` with no loggin…
18.1s4096 output tokens
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
Frequently asked questions
- Which is cheaper, Claude Haiku 5.5 or GPT-5.6 Sol?
- Per 1M output tokens, Claude Haiku 5.5 is $0.5275 and GPT-5.6 Sol is $11.00 on FastMetal (US dollars, before tax), so Claude Haiku 5.5 is cheaper.
- How do the context windows of Claude Haiku 5.5 and GPT-5.6 Sol compare?
- Claude Haiku 5.5 takes 1,000,000 tokens; GPT-5.6 Sol takes 1,050,000.
- Can I use Claude Haiku 5.5 and GPT-5.6 Sol with the same API key?
- Yes. On FastMetal's OpenAI-compatible endpoint, switch by passing "anthropic-claude-haiku-5-5" or "gpt-5.6-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 Claude Haiku 5.5 and GPT-5.6 Sol from the browser chat and the API. No monthly fee.