Claude Sonnet 4.5 API cost calculator
Claude Sonnet 4.5 (Anthropic) is priced at $3 per million input tokens, $0.3 for cached input, and $15 per million output tokens — half that through the Batch API. Verified 2026-09-17 against Anthropic's pricing page.
What Claude Sonnet 4.5 costs for common workloads
| Workload | Per request | Per day | Per month |
|---|---|---|---|
| Support chatbotShort turns with a reused system prompt — 3k in, 400 out, 60% cached. | $0.010 | $50.70 | $1,521 |
| RAG over documentsRetrieved context dominates — 12k in, 500 out, 30% cached. | $0.034 | $50.67 | $1,520 |
| Coding agentGrowing context every turn — 20k in, 1.5k out, 80% cached. | $0.039 | $118 | $3,537 |
| Batch classificationTiny prompts at volume through the Batch API — 800 in, 20 out. | $0.0014 | $270 | $8,100 |
Its blast radius when an agent loops
The coding-agent workload above at 30 requests a minute — $70.74 an hour — priced at each point a team usually finds out:
Hourly alert
$70.74
Next morning
$1,698
After a weekend
$4,244
Monthly invoice
$50,933