How much does the Claude Opus 4.5 API cost?

Claude Opus 4.5 costs $5 per million input tokens and $25 per million output tokens, with cached input at $0.5 per million. A workload of 10M input and 1.5M output tokens per month costs about $87.50.

What is the context window of Claude Opus 4.5?

Claude Opus 4.5 supports a context window of 200,000 tokens (200K), with up to 64K output tokens per response.

Is Claude Opus 4.5 open source?

No — Claude Opus 4.5 is a proprietary model available through Anthropic's API and partner platforms.

What are the best alternatives to Claude Opus 4.5?

The closest alternatives by overall capability are Qwen3-Max, GPT-5.5, Gemini 3 Pro, Gemini 2.5 Pro. See the comparison pages for detailed head-to-head breakdowns.

Claude Opus 4.5

Name: Claude Opus 4.5
Price: 5 USD
Author: Anthropic

Anthropic·Nov 2025reasoningproprietary

Claude Opus 4.5 was a landmark release: the first model to clear 80% on SWE-bench Verified, while simultaneously cutting Opus pricing from $15/$75 to $5/$25 per million tokens. That price reset reshaped the frontier-model market and made Opus viable as a daily coding-agent driver rather than a special-occasion model. Within Anthropic's lineup it has been superseded by the 4.6–4.8 series, which kept its pricing.

Benchmark results

Where it shines

Historic price-performance reset for frontier models
Excellent coding, agentic and long-horizon task ability
Widely benchmarked and well understood

Alternatives to Claude Opus 4.5

Qwen3-Max

Alibaba's trillion-parameter API flagship — frontier-adjacent quality with strong agentic tool use at mid-tier prices.

GPT-5.5

OpenAI's flagship reasoning model with a 1M-token context window, built for hard coding, science and long-horizon agentic work.

Gemini 3 Pro

Google's November 2025 frontier breakout — 91.9% GPQA Diamond and 37.5% HLE made it the reasoning leader of its generation.

Gemini 2.5 Pro

Google's 2025 workhorse flagship — first mainstream thinking model with a 1M context, still widely deployed.

Frequently asked questions

How much does the Claude Opus 4.5 API cost?: Claude Opus 4.5 costs $5 per million input tokens and $25 per million output tokens, with cached input at $0.5 per million. A workload of 10M input and 1.5M output tokens per month costs about $87.50.
What is the context window of Claude Opus 4.5?: Claude Opus 4.5 supports a context window of 200,000 tokens (200K), with up to 64K output tokens per response.
Is Claude Opus 4.5 open source?: No — Claude Opus 4.5 is a proprietary model available through Anthropic's API and partner platforms.
What are the best alternatives to Claude Opus 4.5?: The closest alternatives by overall capability are Qwen3-Max, GPT-5.5, Gemini 3 Pro, Gemini 2.5 Pro. See the comparison pages for detailed head-to-head breakdowns.