Anthropic has confirmed Claude Haiku 5.5, and it has not said when. The official line is the same sentence that confirmed Sonnet 5.5, in the September 22, 2026 Claude Opus 5.5 announcement: “Claude Sonnet 5.5 and Claude Haiku 5.5 will follow in the coming weeks”. As of September 23, 2026, 14:40 UTC, Anthropic’s model documentation lists Claude Haiku 4.5, claude-haiku-4-5-20251001, as the current Haiku, and no Haiku 5.5 identifier, price or model card exists anywhere Anthropic publishes.
The Haiku story has a twist the others do not. For six weeks before that sentence, the rumor was about a Haiku 5, predicted for next week twice. It never shipped, and Anthropic skipped the number.
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Claude Haiku 5.5 is confirmed and undated. Anthropic’s September 22, 2026 Opus 5.5 announcement says Sonnet 5.5 and Haiku 5.5 will follow in the coming weeks. No identifier, price, model card or benchmark exists as of September 23.
There is no Haiku 5. From August 12 one X account posted that a Haiku 5 would arrive within weeks, then next week on August 22 and again on September 8. Neither week produced a model, and Anthropic’s next Haiku carries the number 5.5.
Claude Haiku 4.5 is still the current Haiku, released October 15, 2025, 343 days before this page opened, at $1 per million input tokens and $5 output. It is the longest-serving current model in Anthropic’s lineup.
The price claims are ratios, not prices. The August posts said about 20 times cheaper than Opus 5; that would be $1.25 per million output tokens. Haiku 4.5 is already 5 times cheaper than Opus 5 on output. The September 23 post says Haiku 5.5 could match Opus 5.5 and beat Fable 5.1.
CellCog does not route to Haiku today; every Claude tier runs on Claude Opus 5.5. A Haiku 5.5 near Opus 5.5 at a fraction of the price would be a same-day evaluation for our fast tiers, and this page becomes its release record on this URL.
§ 01What we actually know
| Claim | Status |
|---|---|
| Haiku 5.5 exists and is coming | Anthropic, September 22: in the coming weeks |
| Release date | None given |
| Model identifier | None; claude-haiku-4-5-20251001 is current |
| Price | Not published; Haiku 4.5 lists $1 input and $5 output per million tokens |
| Haiku 5 launching next week | X posts, August 22 and September 8; neither happened |
| About 20 times cheaper than Opus 5 | X posts, August 12 and 17; no document |
| 1M-token context window | X posts, August and September; no document |
| Opus 5.5 level, beats Fable 5.1 | X post, September 23; no benchmark |
| Already finished, waiting for release | X post, September 23; no source named |
§ 02What Anthropic said, word for word
One sentence: “Claude Sonnet 5.5 and Claude Haiku 5.5 will follow in the coming weeks”. It names the model and the family, and nothing else. The same page describes the model Haiku 5.5 will be compared with: Opus 5.5 “performs at the level of Claude Fable 5.1 on most work”.
§ 03The Haiku 5 that never came
| Date | Event | Source |
|---|---|---|
| Aug 12, 13:42 | Haiku 5 public release within the next few weeks, near Opus 5 | @Mr_Salio on X |
| Aug 17, 13:46 | Release within the next few weeks, about 20 times cheaper | @Mr_Salio on X |
| Aug 22, 13:47 | Haiku 5 reportedly launching next week | @Mr_Salio on X |
| Aug 29 | The week named on August 22 ends; no Haiku | Our read |
| Sep 8, 13:46 | Haiku 5 could launch next week, near Fable 5.1 | @Mr_Salio on X |
| Sep 15 | The week named on September 8 ends; no Haiku | Our read |
| Sep 22, 16:31 | Sonnet 5.5 and Haiku 5.5 follow in the coming weeks | Anthropic |
| Sep 23, 12:05 | Haiku 5.5 leak: Opus 5.5 level, already finished | @Mr_Salio on X |
| Sep 23, 14:40 | Docs, release notes, pricing, OpenRouter catalog: no Haiku 5.5 | Our read |
On August 22 the post read “Reportedly launching next week”. On September 8: “Haiku 5 could reportedly launch next week”. The first named week ended 25 days before this page opened, the second 8 days before. After Anthropic’s announcement the same account posted a Haiku 5.5 leak, “Also Could be Opus 5.5 level and Beat Fable 5.1”, and one reply said what the thread needed: “anthropic already said haiku 5.5 is coming in a few weeks, where’s the leak?”
§ 04What the price claims mean
The rumors describe Haiku as a ratio of other models, so here are the ratios against Anthropic’s live price list.
| Model | Output per million tokens | Source |
|---|---|---|
| Claude Haiku 4.5 (current) | $5 | Anthropic pricing |
| Claude Sonnet 5 | $10 | Anthropic pricing |
| Claude Opus 5.5 | $20 | Anthropic pricing |
| Claude Fable 5.1 | $50 | Anthropic pricing |
| 20 times cheaper than Opus 5, as rumored | $1.25 | Arithmetic on the rumor |
Haiku 4.5 is already 5 times cheaper than Opus 5 on output ($5 against $25). A Haiku at 20 times cheaper would undercut its own predecessor by three quarters. Against Opus 5.5 the same ratio would mean $1.00. Anthropic has cut prices this cycle, so the direction is plausible; the size is a claim with no document.
§ 05What Anthropic’s own rhythm says
Haiku 4.5 was first listed on October 15, 2025, 16 days after Sonnet 4.5, and has been the current Haiku for 343 days. In the same span Sonnet went through 4.5, 4.6 and 5. The last .5 family shipped Sonnet, then Haiku, then Opus within 56 days. This time Opus shipped first, and Anthropic has not said whether Sonnet or Haiku comes next.
§ 06What would confirm it
- A new identifier in Anthropic’s model documentation beside claude-haiku-4-5-20251001.
- A Haiku 5.5 row on Anthropic’s pricing page.
- An entry in the platform release notes.
- A catalog line on Bedrock, Google Cloud, Foundry or OpenRouter.
- A system card or an Anthropic announcement page.
§ 07Where CellCog stands
CellCog does not route to Haiku today: every Claude tier runs on Claude Opus 5.5 since its release day (what changed), and our fastest tiers run on a Gemini Flash model. A Haiku 5.5 close to Opus 5.5 at a fraction of the price would be evaluated on its release day for exactly those fast tiers, and the result would land here.
§ 08What we are watching for
- Anthropic’s model docs, pricing and release notes on every scan.
- Provider catalogs for a new claude-haiku identifier.
- A published context window and price, and whether the 20x claim survives contact with the price list.
- Independent speed and quality scores after release.
- Whether Haiku or Sonnet ships first.
§ 09The tracker
As of September 23, 2026, 14:40 UTC: Haiku 5.5 is confirmed by name, undated and unpriced. The Haiku 5 predicted for next week in August and September never shipped. Haiku 4.5 is the current model.
§ 10Update log
As of September 23, 2026, 14:40 UTC: page opened.
§ 11Sources
- Anthropic, Introducing Claude Opus 5.5, September 22, 2026.
- Anthropic, models overview, pricing and release notes, read September 23, 2026, 14:40 UTC.
- OpenRouter, Anthropic catalog, read September 23, 2026, 14:40 UTC.
- X: @Mr_Salio, August 12, August 17, August 22, September 8 and September 23; @editxshub, September 23. Read directly; times from the post ids.
Q1Has Anthropic confirmed Claude Haiku 5.5?
Yes, by name, without a date. The September 22, 2026 Claude Opus 5.5 announcement says Claude Sonnet 5.5 and Claude Haiku 5.5 will follow in the coming weeks. Anthropic’s model documentation, pricing page and release notes, read September 23, have no Haiku 5.5 entry.
Q2What happened to the Haiku 5 leaks?
They missed. One X account posted four Haiku 5 claims between August 12 and September 8, 2026, two of them saying next week. No Haiku 5 shipped, and after Anthropic named Haiku 5.5 on September 22 the same account posted a Haiku 5.5 leak. A reply asked where the leak was, since Anthropic had already said it.
Q3Will Haiku 5.5 beat Opus?
That is a September 23, 2026 X post, with no benchmark behind it. Anthropic has published no Haiku 5.5 scores. The claim to test on release day is whether it holds up against Claude Opus 5.5, which Anthropic says performs at the level of Claude Fable 5.1 on most work.
Q4How old is Claude Haiku 4.5?
Released October 15, 2025, it was 343 days old on September 23, 2026. Sonnet has had three versions in that time: Sonnet 4.5, 4.6 and 5.
Q5Should I wait for Haiku 5.5?
If you run high-volume, low-latency work, a new Haiku is worth watching, but Haiku 4.5 is live at $1 and $5 per million tokens and a 5.5 would arrive as a new identifier. For agent work, the layer around the model matters more than the version: memory that survives the conversation, a task board and approvals a human can see.