Comparison · Chat & code models
Claude Opus 5.5 vs GPT-6 Sol
Claude Opus 5.5 or GPT-6 Sol? Opus costs about 2.5x more per token. How they differ on caching, Claude Code, context and thinking, and when Opus pays off.
Specs side by side
| Claude Opus 5.5 | GPT-6 Sol | |
|---|---|---|
| Vendor | Anthropic | OpenAI |
| Type | Chat & code | Chat & code |
| Released | 2026-09 | 2026-09 |
| Context window | 1,000,000 tokens | 1,050,000 tokens |
| Max output | 128,000 tokens | 128,000 tokens |
| Endpoints | /v1/chat/completions · /v1/messages | /v1/chat/completions |
Price per token
| Claude Opus 5.5 | GPT-6 Sol | |
|---|---|---|
| Input / 1M tokens | $5.40 | $2.16 |
| Output / 1M tokens | $27.00 | $10.80 |
| Cached input / 1M | input rate | $0.216 |
| 1,000 replies (1,500 in + 400 out) | $18.90 | $7.56 |
Prices exclude taxes and are charged from your prepaid USD balance. Both models work through the same key, in the OpenAI-compatible /v1/chat/completions endpoint. Failed generations cost nothing.
Use GPT-6 Sol as the default model for code, agents and document analysis when you count the cost of every request: per token it is about 2.5 times cheaper than Claude Opus 5.5, and it has a separate, low cached-input rate. Use Claude Opus 5.5 for long Claude Code sessions and large repository changes, where one fewer mistake is worth more than the price gap. Both have a context window of about 1M tokens and up to 128K output tokens, so price, tooling and your own tests decide, not limits.
Key differences
- Price. Claude Opus 5.5 costs $5.40 / $27.00 per 1M tokens, GPT-6 Sol costs $2.16 / $10.80 per 1M tokens. Opus is about 2.5 times more on both input and output, so the 1,000-reply row in the table above is 2.5 times higher too.
- Caching. GPT-6 Sol has a separate cached-input rate on Jantaris, ten times lower than regular input. Claude has no such line, so a repeated prefix is billed as input. With a long, stable system prompt, Sol's lead grows.
- Endpoints. Opus works on
/v1/chat/completionsand on the Anthropic-compatible/v1/messages, so it runs in Claude Code. Sol runs on the OpenAI-compatible endpoint: Cursor, Cline or n8n yes, Claude Code no. - Thinking. Both are reasoning models and thinking tokens are billed as output. On Opus 5.5 adaptive thinking cannot be switched off, so a short answer to a hard question can cost more than its length suggests.
- Context. Sol: 1,050,000 tokens, Opus: 1,000,000. No practical difference.
- Position in the family. Anthropic puts Opus 5.5 at Fable 5.1 level on most work at a lower price. OpenAI places Sol below the flagship GPT-6 Astra, for hard tasks you want to iterate on many times without paying flagship rates.
When to pick Claude Opus 5.5
- Agent sessions in Claude Code that run for hours. Setup is in Claude Code with a custom base URL.
- Refactors and migrations that touch hundreds of files.
- Technical writing that has to follow a house style guide.
- Code already written for the Anthropic SDK: you change only the base URL and key.
When to pick GPT-6 Sol
- A default model for internal tools, code and tool-calling agents when you pay for every iteration.
- Long contracts and reports where the same long prefix comes back in many requests.
- Code built on the OpenAI SDK, for example moving from GPT-5.6 Sol with nothing but the
modelfield changed. - High traffic, where Opus's 2.5x rate adds up fast.
My rule is simple: Sol by default, Opus for the tasks where Sol falls short on my own examples. Both models sit behind one key and one balance, so switching is one field in the request. Full family pricing is in Claude Opus 5.5 API pricing and GPT-6 API pricing.
FAQ
Claude Opus 5.5 or GPT-6 Sol: which is better for coding?
For long agentic work in Claude Code I would pick Opus 5.5, because of the two only Opus works through /v1/messages. For code in Cursor or your own agent on the OpenAI SDK, start with Sol and route to Opus only the tasks Sol gets wrong. The best test is a dozen tasks from your own repository run through both.
How much more expensive is Opus 5.5 than GPT-6 Sol?
About 2.5 times on every input and output token. With a repeated prefix the gap is wider, because Sol has a low cached-input rate and Claude bills that prefix as regular input. Current rates: $5.40 / $27.00 per 1M tokens and $2.16 / $10.80 per 1M tokens.
Can I use GPT-6 Sol in Claude Code?
Not through Jantaris. Claude Code speaks the Anthropic Messages format, and that endpoint serves Claude models only. Use GPT-6 Sol in OpenAI-compatible tools such as Cursor, Cline or n8n.
Which has the larger context window?
Practically the same: GPT-6 Sol has 1,050,000 tokens, Opus 5.5 has 1,000,000. Both return up to 128K output tokens.
What about GPT-6.1 Sol?
OpenAI released GPT-6.1 Sol on September 29 as an update to Sol at the same base price. The Jantaris catalog serves gpt-6-sol for now. The live list is at GET /v1/models?category=chat.