Claude Haiku 5.5

What it is

Claude Haiku 5.5 is a large language model from Anthropic, released on 7 October 2026 with the API ID claude-haiku-5-5. It was the third model in the Claude 5.5 family. Anthropic called it "the cheapest, fastest, and most capable small model we've ever released". ^[1]

Price

Haiku 5.5 uses tiered pricing. Prompts of up to 100K tokens cost $0.10 per million input tokens and $0.50 per million output tokens. Prompts above 100K tokens cost $0.50 per million input tokens and $2.50 per million output tokens. For comparison, Claude Haiku 4.5 cost $1 per million input tokens and $5 per million output tokens. Anthropic said Haiku 5.5 costs about 75% less to run on average. ^[1][3]

Capability

The model has a 1M-token context window, a maximum output of 128K tokens, and a June 2026 knowledge cutoff. ^[2]

Anthropic compared Haiku 5.5 with Haiku 4.5 on several benchmarks. On GDPval-AA v2.1 it reached 1620 Elo, against 735. On the offline subset of OSWorld 2.1 it scored 72.4%, against 15.7%. On Humanity's Last Exam with tools it scored 57.4%, against 18.7%, and on Terminal-Bench 4.0 it scored 39.2%, against 0.0%. ^[1]

Haiku 5.5 is the first Haiku-class model with an adjustable effort setting, which ranges from Low to Max. ^[1]

Uses

Anthropic aimed the model at high-volume work such as summaries, compaction, database queries and classification. It also positioned it as a subagent to work alongside Opus 5.5 and Sonnet 5.5. ^[1]

The model uses an updated tokenizer. It also adds beta support for computer use and browser use in the Python and TypeScript SDKs. ^[1]

Safeguards

Haiku 5.5's cyber safeguards are stricter than those of Haiku 4.5 but looser than those of Sonnet 5.5. Its biology safeguards match those of Sonnet 5, Sonnet 5.5 and Opus 5. ^[1]

Availability and position in the timeline

Haiku 5.5 is available on Amazon Web Services, Google Cloud, Microsoft Azure and the Claude Platform. Its retirement is not scheduled before 7 October 2027. ^[1][4]