Comparison · Anthropic and OpenAI
Claude Sonnet 5.5 vs GPT-5.4
Listed API prices of Claude Sonnet 5.5 and GPT-5.4 turned into the cost of the same three standard tasks and what each provider’s API documentation says about features that break on a switch. Output quality, speed and answer length are not compared.
Calculated impact cost per task and per month
For an L2 task (deep analysis over a 50,000-token document, 3 steps), Claude Sonnet 5.5 costs $0.348 and GPT-5.4 $0.443 at the prices listed in the United States on , so Claude Sonnet 5.5 is 21.4 % less than GPT-5.4, counting visible output only, without cache discounts or hidden reasoning.
| Task | Claude Sonnet 5.5, per task | GPT-5.4, per task | Claude Sonnet 5.5, per month | GPT-5.4, per month | Claude Sonnet 5.5 vs GPT-5.4, per task |
|---|---|---|---|---|---|
| L1Micro-task (classification or strict JSON extraction) | $0.0050per L1 task | $0.0067per L1 task | $73.00per month | $98.55per month | −25.9 % |
| L2Deep analysis over a 50,000-token document | $0.348per L2 task | $0.443per L2 task | $5,080.80per month | $6,460.50per month | −21.4 % |
| L3Agentic coding loop, 15 steps | $2.72per L3 task | $3.42per L3 task | $39,726.60per month | $49,986.75per month | −20.5 % |
Calculated Per month: 20 tasks an hour around the clock, 730 hours.
Prices USD per 1M tokens
| Price | Claude Sonnet 5.5 | GPT-5.4 |
|---|---|---|
| Input, per 1M tokens | $2.00 | $2.50 |
| Output, per 1M tokens | $10.00 | $15.00 |
| Price from | Provider's price list · source page Published | OpenRouter · source page (data) Published |
| Read | · the United States | · the United States |
| Context window | 1,000,000 tokens | 1,050,000 tokens |
What can I use it for? six common tasks, our data checks
Quality on your task: not measured by Measured Lab yet.
| Task | Claude Sonnet 5.5 | GPT-5.4 |
|---|---|---|
| Answer customer messages | Fits on price and context | — |
| Pull data from invoices and documents with strict JSON and page images | Fits on price and context | — |
| Summarize documents and meetings | Fits on price and context | — |
| Translate content | Fits on price and context | — |
| Chat assistant on your website | Fits on price and context | — |
| Write and review code with tool calls | Fits on price and context | — |
| Tasks it fits | 6 of 6 | — |
Checks of our data for six common tasks: a published price, a context window and answer length for the task and, where the task needs them, strict JSON output, page images and tool calls; prices, cost a month and terms for each model on its model card. GPT-5.4 is not in the model picker. Compare models for your own task in the model picker.
What breaks when you switch Published provider documentation
Moving from Anthropic to OpenAI: every feature that Anthropic’s documentation lists as supported is also listed as supported by OpenAI.
Moving from OpenAI to Anthropic: every feature that OpenAI’s documentation lists as supported is also listed as supported by Anthropic.
| Feature of the API | Anthropic | OpenAI |
|---|---|---|
| Strict JSON schemas | Yes | Yes |
| Parallel tool calls | Yes | Yes |
| Streamed tool arguments | Yes | Yes |
| Reasoning with tools | Yes | Yes |
| Cache covers tool definitions | Yes | Yes |
What each provider’s own API documentation says, read ; “not stated” is not the same as “no”. Quotes and sources: what breaks when you switch AI APIs.