Claude Haiku 5.5 vs Opus 5.5

The differences that matter

Haiku 5.5 is positioned for frequent, latency-sensitive tasks. Opus 5.5 is positioned for longer-running coding and knowledge work. Their context capacities match, but their reasoning defaults and token rates differ.

Checked October 8, 2026 against the Haiku specification and Opus specification. Opus also has a separately priced fast mode, so these standard-speed categories are not a universal speed ranking.

Understand the 40× base-rate difference

For equal uncached input and output token counts within Haiku's lower-price tier, Opus's listed rates are forty times higher. A 20,000-input, 2,000-billable-output request gives a model-token estimate of $0.003 for Haiku and $0.12 for Opus.

Above 100,000 input tokens, Haiku's higher tier changes that same-token gap to eightfold. Caching, reasoning, fast mode, tools and answer length can change the actual bill. The published Opus rates are therefore a starting point for comparison, not a fixed price for completing any particular job.

A cheap result that must be discarded is not a successful completion. Compare the proportion of usable results and required checking alongside token spend. For repetitive work that passes your checks, the base-rate gap makes testing Haiku worthwhile. For a difficult one-off investigation, quality and completeness may decide the choice. The HaikuChat pricing page covers this workspace's credit packs separately.

Compare complex reasoning without inventing a score

The Opus model description emphasizes longer-running coding and knowledge work. That positioning is a reason to include it in an evaluation, not a measured promise about your task.

The Haiku release table used in our Sonnet comparison does not provide a matching Opus column. We do not transplant an Opus score from another version, mix unrelated benchmarks into a single ranking, or claim to have run a head-to-head test.

For open-ended work, define a rubric: did the answer identify the important constraints, distinguish evidence from assumptions, address counterexamples and make a recommendation you can trace to the supplied material? Score factual errors separately from presentation. A longer answer is not automatically a better investigation.

When Haiku is enough, and when to evaluate Opus

Narrow extraction: pulling an invoice date, total and client name is a constrained task. Start with Haiku and check the fields. Escalate because of an observed ambiguity or failure, not because the source document looks professional.

A cross-document decision: comparing several proposals with conflicting requirements, dependencies and incomplete evidence is different. Test Opus if the output must reconcile those tensions and explain what would change the recommendation. Ask for citations to your supplied passages, and verify them.

Debugging an unfamiliar system: a short error explanation and a sustained root-cause investigation are different workloads. Test a stronger model for the latter, especially when it must weigh several hypotheses. This does not mean it can inspect files or run tests through HaikuChat; those capabilities depend on the separate tool where the model is used.

Repeatable daily work: if every request has a stable input and a known output format, investing in clearer task instructions and checks may be more useful than choosing the largest model. The smaller-model trade-off in Haiku vs Luna may be more relevant.

Use a clear escalation rule

Write the rule before the result arrives. For example: accept a field extraction only if every required value matches the source or is explicitly marked missing; escalate a proposal analysis if it leaves a named constraint unanswered. This stops polished wording from hiding an incomplete task.

Use Haiku for the narrow pass, review the result, and send unresolved work to the tool or model that fits it. Keep a record of what failed and whether the next model actually resolved it. This is a workflow you can evaluate manually, not an automatic Opus-routing feature in HaikuChat.

If you want a middle option before Opus, read Haiku 5.5 vs Sonnet 5.5. If your next task is a short chat, summary or table, open HaikuChat. You can also return to all model comparisons to choose by workload.

Questions about this comparison