Claude Haiku 4.5 vs Sonnet 4.6

The version-specific baseline

The exact models here are claude-haiku-4-5-20251001 and claude-sonnet-4-6. Their numbers belong to different model families; the decimal suffix does not mean Sonnet is simply the next Haiku release.

Sources: Haiku 4.5 model documentation and Sonnet 4.6 model documentation, checked October 8, 2026. These models are listed as active legacy versions. A retirement commitment is not a promise that a particular chat service will offer a model indefinitely.

Compare usable work, not just a threefold rate gap

Holding usage at 20,000 input and 2,000 billable output tokens gives uncached model-token estimates of $0.03 for Haiku 4.5 and $0.09 for Sonnet 4.6. The threefold difference describes the published base rates, excluding caching, discounts, tools and retries.

For repeated processing, track accepted outputs per batch. If Haiku finishes a narrow extraction accurately, paying more provides no automatic advantage. If a difficult source repeatedly produces omissions, a more expensive request can be worthwhile when it reduces failed attempts and editing. That conclusion needs observed results, not a model-family slogan.

Do not apply Haiku 5.5's much lower starting rates to this older Haiku version. Similarly, Sonnet 5 and Sonnet 5.5 rates do not describe Sonnet 4.6. Version-specific budgeting prevents an apparently cheap plan from relying on prices for a different model.

Use different checks for three common tasks

Summary of a short email chain: prepare an expected list of decisions, owners and open questions. Check whether the answer preserves a postponed deadline and attributes a proposal to the right person. A smoother writing style is secondary to preserving those facts.

Extraction from a screenshot: include a low-contrast date and an absent reference number. Require explicit uncertainty for unreadable text and an empty or missing marker for the absent field. Both models accept images, but that capability does not establish accuracy on your image. Check every requested value against it.

A cross-document analysis: ask how a later amendment affects an earlier requirement. Sonnet's larger context capacity can accommodate more source material, but correctness still requires finding the relevant amendment and applying it consistently. Provide a rubric that names the expected relationships, not just a word count.

These are proposed evaluation cases. We have not run a controlled Haiku-4.5-versus-Sonnet-4.6 study, and do not publish a numerical accuracy or latency ranking for them.

Reasoning settings can hide an unfair comparison

Haiku 4.5's extended-thinking control and Sonnet 4.6's adaptive thinking are not interchangeable. If one tool enables additional reasoning while another returns a quick answer, your comparison includes both the model and the configuration.

Write down the settings you can see and whether retrieval, browsing or code execution was available. Use the same source material and requested deliverable. Measure time until the complete answer is useful, then count corrections. A fast first token can still lead to a long or inaccurate answer.

For an existing automated workflow, validate supported controls and output handling before changing versions. For someone choosing a browser workspace, focus on the actual tools and limits exposed in that product rather than assuming every published model feature is available there.

Keep the legacy decision separate from today's shortlist

An earlier version may remain useful when its behavior has been evaluated and your process depends on it. Review lifecycle status and plan a tested replacement rather than waiting for an availability problem.

If you need the next Sonnet step, compare Haiku 4.5 with Sonnet 5. If you are choosing a fresh workflow, start with Haiku 5.5 vs Sonnet 5.5 or the three-family selection guide. Those guides use current model specifications instead of silently updating the figures in this older pairing.

HaikuChat defaults to Haiku 5.5 for chat, summaries and table extraction, with Haiku 4.5 also available. Open the workspace to see connection status and task limits, and check its own pricing for credits. This comparison does not add Sonnet 4.6 as a workspace option.

Questions about this comparison