How much does the Claude API itself cost on a typical project?

Tiny, usually under 5% of project total. A 4-week Project Sprint typically burns < $200 in Anthropic API charges (Claude Sonnet 4.6 with prompt caching enabled). On a $2,499 sprint, that’s < 8% of cost. We bill the API charges back at-cost (or include them in the fixed price, your choice). Anthropic charges $3 / $15 per million input/output tokens for Sonnet. With prompt caching, repeated reads of db_schema.xml and vendor/magento/ drop 90% of input cost.