Speaking of cost, Haiku 4.5 is included in the subscription price of Claude's web and app plans. Through the API (for developers), the small model costs $1 per million input tokens and $5 per million output tokens. This compares to Sonnet 4.5 at $3 per million input and $15 per million output tokens and Opus 4.1 at $15 per million input and $75 per million output tokens.
This model serves as a lower-cost replacement for two older models, Haiku 3.5 and Sonnet 4. “Users who rely on artificial intelligence to solve real-time, low-latency tasks, such as chat assistants, customer service agents, or pair programming, will appreciate Haiku 4.5's combination of high intelligence and remarkable speed,” says Anthropic. writes.
Claude 4.5 Haiku answers Ars Technica's classic AI question: “Would this color be called 'purple' if the city of Magenta didn't exist?”
On SWE stand testedIn a test that measures performance on coding tasks, Haiku 4.5 scored 73.3 percent, compared to Sonnet 4's comparable performance of 72.7 percent. The model is also reported to outperform Sonnet 4 in some tasks such as using computersaccording to Anthropic criteria. Claude Sonnet 4.5, released at the end of September remains Anthropic's cutting-edge model and what the company calls “the best coding model available.”
Haiku 4.5 also surprisingly comes close to what OpenAI GPT-5 can achieve in this particular test suite (as seen in the chart above), although since the results are self-reported and potentially selected based on the model's strengths, they should always be taken with a grain of salt.
However, creating a small, functional coding model can have unexpected benefits for agent-based coding systems such as Claude Code. Anthropic designed Haiku 4.5 to work alongside Sonnet 4.5 in multi-model workflows. In this configuration, Anthropic says, Sonnet 4.5 can break complex problems into multi-step plans and then coordinate multiple instances of Haiku 4.5 to execute subtasks in parallel, such as dedicating workers to completing tasks faster.
For more details on the new model, Anthropic has published system card And documentation for developers.
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