Claude Opus 4.5
Previous flagship Claude with strong reasoning capabilities. Great balance of intelligence and accessibility.
About Claude Opus 4.5
Claude Opus 4.5 earns its place at the top of Anthropic's lineup through two things that rarely coexist: frontier coding ability and a price tag that makes production deployment plausible. Its 80.9% score on SWE-bench Verified is the highest recorded among frontier models, and developers describe the output as surgical — targeted changes that actually work rather than verbose rewrites that need to be cleaned up afterward. The 3x price drop from its predecessor ($5/$25 per million tokens input/output vs. $15/$75) combined with using 48–76% fewer output tokens per response means real workloads cost dramatically less than the headline rate implies. Extended thinking mode, computer use support, and a 200K-token context window round out an unusually capable agent platform. The honest caveat: some production teams report noticing a quality dip weeks after deployment, and the model still generates significantly more output tokens than some alternatives, so practical cost comparisons need to account for verbosity. If autonomous coding pipelines, long-context research, or office automation are central to your work, Opus 4.5 is built for exactly that.
Best for
- Automated software engineering — generating PRs, fixing bugs, and refactoring across 7+ programming languages with best-in-class SWE-bench accuracy
- Autonomous agents and computer use — multi-step tool-calling workflows where the model needs to reason, plan, and interact with interfaces
- Deep research and long-document synthesis — 200K-token context with strong long-context reasoning for multi-document analysis and complex problem-solving
- High-volume production APIs — lowest per-token pricing in Anthropic's flagship tier combined with token efficiency makes it viable at scale
- Spreadsheet and office automation — noted improvements in structured data tasks and slide generation over prior Claude versions
Specs & capabilities
How Claude Opus 4.5 stacks up — intelligence, speed, context, and modalities.
Intelligence
High
Speed
Slow
Context window
200,000 tokens
Max output
64,000 tokens
Knowledge cutoff
March 2025 [
Frequently asked questions
What does Claude Opus 4.5 cost?
$5.00 per million input tokens and $25.00 per million output tokens. Prompt cache writes are $6.25/M and cache hits drop to $0.50/M — a significant saving for repeated-context workloads.
How large is the context window?
200,000 tokens input with a maximum of 64,000 output tokens per response. Automatic context summarization also allows conversations to extend beyond the hard context limit.
Does it support reasoning / extended thinking?
Yes. Extended thinking mode activates an internal chain-of-thought process. Note that it adds roughly 16 seconds of time-to-first-token latency compared to the standard mode's ~1.6 seconds.
How does it compare to Claude Sonnet 4.5?
Opus 4.5 scores 16 percentage points higher on LiveCodeBench and leads Sonnet on most coding and reasoning evals. It is more expensive but delivers meaningfully stronger results on complex, multi-step tasks.
What are its main limitations?
Some teams report quality feeling inconsistent weeks into production use. It is also more verbose than some competing models, generating roughly 5x more output tokens than certain alternatives, which affects real-world cost calculations.
Who should choose Opus 4.5 over a smaller Claude model?
Teams running autonomous coding agents, complex research pipelines, or extended agentic workflows where task failure is costly. For straightforward chat or simple Q&A, a smaller model will be faster and cheaper with comparable results.