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Claude Haiku 5.5: what is confirmed and what is rumor

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Claude Haiku 5.5 is the next version of Anthropic’s smallest and cheapest Claude model. Anthropic confirmed it on September 22, 2026, in the same announcement that launched Opus 5.5, saying it will arrive “in the coming weeks.” As of September 25 it has no release date, no price and no model ID. Everything else you have read about it is a rumor, and this post sorts the rumors from the record.

The Opus 5.5 launch itself is covered in Claude Opus 5.5 vs Opus 5, Fable 5.1 and Sonnet 5. What is new here is the Haiku side: what Anthropic said, what the leaks claimed, which of those claims already failed, and what Haiku 5.5 might inherit from Opus 5.5.

What has Anthropic confirmed about Haiku 5.5?

One sentence. From Introducing Claude Opus 5.5: “Claude Sonnet 5.5 and Claude Haiku 5.5 will follow in the coming weeks, with many of the same improvements to performance, efficiency, and safety.” Anthropic’s Mike Krieger posted the same message on launch day.

That is the whole official record. On September 25, 2026, Anthropic’s models overview page still lists Claude Haiku 4.5 as the current small model, and there is no Haiku 5.5 entry, price or model ID anywhere in Anthropic’s documentation.

What do the Haiku 5.5 rumors claim?

The rumors came mostly from posts on X, collected and graded by CellCog, OrcaRouter and KuCoin’s news feed. None of the claims below comes with a benchmark, a document or a screenshot of an Anthropic surface.

ClaimWhere it came fromStatus on Sept 25, 2026
A “Haiku 5” ships next week (said on Aug 22, then again on Sept 8)An X account, via CellCogWrong twice. No Haiku 5 was released. Anthropic skipped straight to the name Haiku 5.5.
The Haiku line is being retired; only Fable, Sonnet and Opus get 5.5 versionsAn X account, via OrcaRouterContradicted. Anthropic named Haiku 5.5 on Sept 22.
Haiku 5.5 performs at Opus 5.5 level and beats Fable 5.1An X post, via KuCoinUnverified. No numbers were given.
About 20 times cheaper than Opus 5, around $1.25 per million output tokensX posts, via CellCogUnverified. No price is published.
A 1 million token context windowX posts, via CellCogUnverified. Opus 5.5 has 1M; Haiku 4.5 has 200K.
The model is already finished and waiting to be releasedAn X post, via KuCoinUnverifiable from outside Anthropic.
Rumor sources are linked in the paragraph above and under Sources. “Unverified” means nothing public confirms or rules it out yet.

One check on the price rumor: $1.25 per million output tokens would be a quarter of what Haiku 4.5 costs today ($5). That would be a much bigger cut than the 20% Opus 5.5 got. Possible, but it is the kind of number to wait for, not to budget around.

What did Opus 5.5 change that Haiku 5.5 could inherit?

Anthropic says Haiku 5.5 gets “many of the same improvements.” It did not say which ones. These are the Opus 5.5 changes, from Anthropic’s announcement and docs, as a list of what is at least on the table:

  • Lower per-token prices. Opus went from $5 to $4 per million input tokens and from $25 to $20 per million output tokens, a 20% cut.
  • Cheaper cached input. Cache reads dropped from $0.50 to $0.20 per million tokens.
  • Fewer tokens per job. Anthropic says Opus 5.5 costs about 40% less than Opus 5 on typical workloads.
  • Faster output. More than 30% faster than Opus 5, per Anthropic.
  • A 1 million token context window and up to 128K tokens of output, per the models overview.
  • Adaptive thinking, always on, with a default effort setting of medium.

Treat every item on that list as possible for Haiku 5.5, not promised. Today the gap is real: Haiku 4.5 has a fifth of Opus 5.5’s context window and half its maximum output, and Anthropic has not said whether 5.5 closes it.

Where does Haiku 4.5 stand today?

ModelReleasedInput / output (per million tokens)Context windowMax output
Haiku 4.5Oct 15, 2025$1 / $5200K64K
Opus 5.5Sept 22, 2026$4 / $201M128K
Haiku 5.5Announced, not releasedNot publishedNot publishedNot published
From Anthropic’s models overview and Haiku 4.5 announcement, read September 25, 2026.

Haiku 4.5 is almost a year old, and its knowledge cutoff is February 2025. Anthropic pitched it at launch as offering coding performance similar to Sonnet 4 at one third of the cost. It has not had a refresh since, while Sonnet 5 (June 30) and Opus 5 (July 24) both shipped this summer, which is a big part of why the “Haiku is being retired” rumor sounded believable.

How can you tell when Haiku 5.5 is actually out?

Rumor accounts said “next week” twice and were wrong both times. These four checks are what a real release looks like:

The last one is the one that matters if you run anything on a small model. A model name in your code is a dependency that can start or stop existing on someone else’s schedule. I learned that the slow way when Groq retired the model behind this site’s chat and the health check still said ok.

What should you do before Haiku 5.5 ships?

  • Keep the model name in configuration, not hard-coded, so switching is a setting change.
  • Measure your current cost per task on Haiku 4.5, so there is a baseline to compare against on release day. Price per token is only half of it; the token count was never the metric on its own.
  • Do not plan around rumored prices or context sizes. Wait for the pricing page.
  • If you use a Claude subscription rather than the API, per-token prices do not reach your bill; what changes is how much fits in your usage limits. More on that in Where Claude tokens go.

This post reflects what was public on September 25, 2026. It is a dated record, not a live tracker; when Haiku 5.5 ships, it gets its own post.

Sources