These two models are not really competitors; they are the two ends of a routing table. Haiku 4.5 costs a fifth of Opus 5 on input and handles enormous volume; Opus 5 is what you escalate to when Haiku's answer isn't good enough. Knowing which is which for your workload is worth more than any prompt-engineering trick.
Claude Opus 5 vs Claude Haiku 4.5 at a glance
| Claude Opus 5 | Claude Haiku 4.5 | |
|---|---|---|
| Price (per 1M tokens) | $5 in / $25 out | $1 in / $5 out |
| Context window | 1M tokens | 200K tokens |
| Max output | 128K tokens | 64K tokens |
| Reasoning | Adaptive thinking, five effort levels | Simpler reasoning profile |
| Latency | Slower; long turns are normal | Fastest in the line |
| Best for | Hard, high-stakes, long-horizon work | High-volume, well-specified tasks |
Choose Claude Opus 5 if
- Multi-step reasoning, ambiguous requirements, and anything agentic.
- Prompts that exceed 200K tokens — Haiku physically cannot hold them.
- Tasks where a wrong answer costs more than the token difference.
Choose Claude Haiku 4.5 if
- Classification, extraction, routing, tagging, and summarisation at scale.
- First-line support triage before escalation.
- Anything where latency is the product and the task is well-specified.
The verdict
Use Haiku 4.5 for the volume, Opus 5 for the judgement. A two-tier setup usually costs less than a single mid-tier model and answers better.
Whichever way you lean, run the decision on your own workload rather than a benchmark table. Twenty representative tasks from your real queue will tell you more than any published score.
More on Claude Opus 5
Start with the complete Claude Opus 5 guide for the overview, or go deeper:
Ready to go deeper?
Read the full Claude Opus 5 guideFrequently Asked Questions
Is Haiku 4.5 good enough to replace Opus 5?
For well-specified, repetitive tasks — classification, extraction, routing — often yes, at a fifth of the input price. It is not a replacement for multi-step reasoning, ambiguous requirements, or agentic work, and its 200K context window is a hard ceiling that Opus 5's 1M window does not have.
What is the cheapest way to get Opus 5 quality?
Cascade. Answer with Haiku 4.5 or Sonnet 5, apply a cheap automated check, and escalate only failures to Opus 5. Most workloads have a long tail of easy requests, so the blended cost lands far closer to the cheap model than the expensive one.
Do both models support the same features?
Not entirely. Opus 5 has the full five-level effort ladder, adaptive thinking on by default, the 1M-token context window, and fast mode. Haiku 4.5 targets speed and cost, with a 200K window and a 64K output ceiling.
