Anthropic launched Claude Haiku 4.5 today. It is the most compact variant of this generation of LLMs from Anthropic and promises to deliver performance close to that of GPT-5.
Claude Sonnet 4.5 remains the better-performing model by a considerable margin, but Haiku’s benchmark scores are not too far off from the larger LLM. Claude Haiku 4.5 “gives users a new option for when they want near-frontier performance with much greater cost efficiency.”
It is striking that GPT-5 performs only slightly better than the latest, smallest Claude model in Anthropic’s benchmarks. The question is whether this will also be the case in reality. After all, GPT-5 is capable of scaling up to GPT-5 Thinking for complex issues, which yields different benchmark figures.
Dual use
An interesting suggestion from Anthropic is to use Haiku and Sonnet together. Whereas Sonnet 4.5 can divide a complex problem into multiple steps, Anthropic says, a “team of multiple Haiku 4.5s” can perform the divided tasks.
Where Sonnet 4.5 costs $3 per million input tokens and $15 per million output tokens, Haiku 4.5 costs $1 and $5, respectively.
“Sweet spot”
Anthropic further states that Claude Haiku 4.5 is more than just a cheap alternative for users who cannot afford the more expensive models. “Claude Haiku 4.5 hit a sweet spot we didn’t think was possible: near-frontier coding quality with tremendous speed and cost efficiency,” said Anthropic co-founder Guv Gur-Ari. All told, Haiku achieves about 90 percent of Sonnet’s performance, he said.
AI safety is and remains a priority for Anthropic, at least when presenting new models. Haiku 4.5 is said to behave much more safely than 3.5, its immediate predecessor. In fact, misaligned behaviors were more common in Sonnet 4.5 and Opus 4.1 among the Claude models. All in all, Anthropic believes Haiku 4.5 is the safest model the company has created. So there is still no cause for concern about a shift toward more dangerous AI behavior, something Anthropic CEO Dario Amodei has repeatedly expressed his concerns about.
Claude Haiku 4.5 is available via Anthropic’s API, Amazon Bedrock, and Google Cloud’s Vertex AI. It is a drop-in replacement for Haiku 3.5 and Sonnet 4.