Usage metrics define what gets measured and billed, such as API calls, active users, data stored, messages sent, or compute hours consumed. Choosing the right usage metric is critical because it determines how revenue scales with customer value delivery.

Example: A SaaS data platform uses three usage metrics: rows processed (at $0.001 per 1,000 rows), storage used (at $0.023 per GB/month), and API calls (at $0.0005 each). Each metric independently captures a different dimension of value delivered to the customer.