Claude Sonnet 5 vs Claude Haiku 4.5: cost compared
Last verified
Claude Haiku 4.5 is 50% cheaper on input and 50% cheaper on output than Claude Sonnet 5. Whether that makes it the right choice depends entirely on whether it does your task well enough — this page gives you the cost side of that trade, precisely.
Rates side by side
| $ per million tokens | Claude Sonnet 5 | Claude Haiku 4.5 |
|---|---|---|
| Input | $2.00 | $1.00 |
| Output | $10.00 | $5.00 |
| Cached input | $0.20 | $0.10 |
| Batch input | $1.00 | $0.50 |
| Output : input ratio | 5.0× | 5.0× |
What the difference is worth
Monthly cost for the same workload on each, without caching:
| Workload | Claude Sonnet 5 | Claude Haiku 4.5 | Difference |
|---|---|---|---|
| Support chatbot 1,000 conversations/month · 2,000 in + 500 out each | $9.00 | $4.50 | $4.50 saved |
| RAG search 10,000 queries/month · 8,000 in + 400 out each | $200 | $100 | $100 saved |
| Bulk extraction 10,000 documents · 3,000 in + 300 out each | $90.00 | $45.00 | $45.00 saved |
| Coding agent 100 runs/month · 400,000 in + 20,000 out each | $100 | $50.00 | $50.00 saved |
Which to use
Claude Haiku 4.5 if the task is well-specified and mechanical — extraction, classification, formatting, routine transformation. The saving is real and compounds with volume.
Claude Sonnet 5 if the task involves genuine reasoning, long-horizon planning, or work where a wrong answer is expensive to catch. Paying 2.0× more on input is trivial compared to the cost of shipping a bad result.
Both are Anthropic models, so switching is usually a one-line change and the tokenizer is the same — which makes this a genuinely easy experiment to run. Test on your own workload before deciding.
Don't skip caching
Cached input costs $0.20 on Claude Sonnet 5 and $0.10 on Claude Haiku 4.5. If your prompts share a stable prefix, caching on the more expensive model can beat switching to the cheaper one outright — worth checking before you migrate anything.
Sources
Anthropic rates verified 2026-08-05 (source). Anthropic rates verified 2026-08-05 (source).