GPT-5.5 vs Claude Opus 5
Which one to choose
Pick GPT-5.5 for general coding, computer use and research with OpenAI's hosted tools such as shell, patch application, MCP, web search and file search. Pick Claude Opus 5 for agentic debugging, financial modeling and legal agent work, where Anthropic reports its gains. The deciding factor is the tool environment and domain focus: GPT-5.5 brings a built-in tool list and five effort levels, while Opus 5 uses adaptive thinking and is tuned for professional agent work.
Pricing comparison
| GPT-5.5 | Claude Opus 5 | |
|---|---|---|
| Model maker | OpenAI | Anthropic |
| Delivery availability | Available | Available |
| Context window | 1M | 1M |
| Max output | 128K | 128K |
| Official price | Input$5.00per 1M tokensOutput$30.00per 1M tokens | Input$5.00per 1M tokensOutput$25.00per 1M tokens |
| TokenLab price | Input$1.50per 1M tokensOutput$9.00per 1M tokens | Input$1.50per 1M tokensOutput$7.50per 1M tokens |
| Model performance |
|
|
| Capabilities | CodeJSON modePrompt CacheReasoningTool useVision | JSON modePrompt CacheReasoningTool useVision |
Choose GPT-5.5 when
- You want hosted tools such as a shell, patch application and file search without building them yourself.
- You want to choose among five reasoning levels, from none to xhigh.
- Your knowledge needs reach into late 2025 and you want OpenAI's default frontier model.
Choose Claude Opus 5 when
- You build and audit spreadsheet models or reconcile financial statements.
- Your agents review contract sets and track defined terms across documents.
- You hand it bug reports and expect a reproduced issue, a root cause and a fix with a test.
How they differ
| Aspect | GPT-5.5 | Claude Opus 5 |
|---|---|---|
| Built-in tools | Lists computer use, hosted shell, patch application, MCP, web search and file search. | Supports tool use, with the tool set defined by your own application. |
| Reasoning control | Five effort levels with medium as the default. | Adaptive thinking decides how much to reason per task. |
| Domain focus | General frontier model for coding, computer use, research and knowledge work. | Anthropic reports gains in life sciences, financial modeling and legal agent work. |
| Coding agents | Plans, edits and verifies changes across large repositories with shell commands. | Anthropic reports steadier agentic coding from run to run than earlier Opus models. |
| Lifecycle | OpenAI offers a Pro tier for the hardest questions. | Anthropic's newer Opus 5.5 has replaced it as the current Opus. |
Summary
- GPT-5.5: Input $1.50 / Output $9.00 per 1M tokens; Claude Opus 5: Input $1.50 / Output $7.50 per 1M tokens. Rates depend on the billing unit, specification, and usage. Compare matching conditions in the model's detailed pricing; a single rate does not determine the total cost.
FAQ
Which is better for software engineering agents?
Both target them. GPT-5.5 gives you hosted shell and patch tools out of the box, while Opus 5 gives steadier runs on bug-to-fix work. Pick by whether you prefer OpenAI's tool environment or your own.
Which is better for finance or legal work?
Claude Opus 5, according to Anthropic, which cites gains in financial modeling and legal agent work. GPT-5.5 can do knowledge work too, so test it on your own documents.
Is Claude Opus 5 the latest Opus?
No. Opus 5.5 has replaced it as Anthropic's current Opus, with better results and faster output. Opus 5 remains useful for existing integrations that you have already tested.
Can I swap one for the other without rewriting prompts?
Not without checks. GPT-5.5 relies on effort levels and hosted tools, and Opus 5 relies on adaptive thinking and your own tool definitions, so prompts and tool schemas need re-testing.
Which is cheaper, GPT-5.5 or Claude Opus 5?
GPT-5.5: Input $1.50 / Output $9.00 per 1M tokens; Claude Opus 5: Input $1.50 / Output $7.50 per 1M tokens. Rates depend on the billing unit, specification, and usage. Compare matching conditions in the model's detailed pricing; a single rate does not determine the total cost.
What are the key differences between GPT-5.5 and Claude Opus 5?
GPT-5.5: Code
Sources
Reviewed Oct 2, 2026