// comparison · updated 2026-05-01
Claude Sonnet 4.5 vs Claude Haiku 4.5
when to use which
Pick Claude Sonnet 4.5 when
Multi-step reasoning, agent planning, code review, drafting from rough notes, anything where output quality directly affects user experience.
Anthropic's mid-tier model — best balance of capability + price
https://www.anthropic.com/claudePick Claude Haiku 4.5 when
High-volume triage, classification, simple summarisation, near-realtime processing where latency matters more than nuance.
Anthropic's fastest small model — 5-7x cheaper than Sonnet
https://www.anthropic.com/claudeSide by side
| Feature | Claude Sonnet 4.5 | Claude Haiku 4.5 |
|---|---|---|
| Input price (per M tokens) | $3 | $1 |
| Output price (per M tokens) | $15 | $5 |
| Context window | 200K | 200K |
| Latency (typical) | ~1.5s first token | ~0.3s first token |
| Best for | Quality-sensitive | Volume-sensitive |
When neither is right
Frontier reasoning tasks (research-grade math, complex multi-step proof) — use Opus 4 if available, or accept Sonnet's ceiling.
Honest take
Most production agent stacks should use both. Triage with Haiku, escalate to Sonnet only when the triage flags ambiguity. The hybrid pattern saves 60-80% vs all-Sonnet without losing quality on the hard cases.
Citations
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Claude Sonnet 4.5 pricing as of May 2026 is $3/M input and $15/M output tokens.
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Claude Haiku 4.5 pricing as of May 2026 is $1/M input and $5/M output tokens.
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Hybrid Haiku-then-Sonnet patterns reduce production API spend 60-80% without measurable quality loss in most agent benchmarks.