--- title: "Measure cost per customer over the last 12 ยท Agent Wranglers" url: https://agentwranglers.se/playbook/due-diligence/operations-and-growth/cost-per-customer id: TDD-14 level: Recommended updated: 2026-10-27 build: a2a6bdfed830 tokens: 512 licence: "CC BY 4.0" licence_url: https://creativecommons.org/licenses/by/4.0/ --- # Measure cost per customer over the last 12 months For AI agents: the [site map](https://agentwranglers.se/llms.txt) lists everything here, and this page sits under [Operations and growth](https://agentwranglers.se/playbook/due-diligence/operations-and-growth.md). By [Agent Wranglers](https://agentwranglers.se/authors/agent-wranglers.md). Updated 2026-10-27. - ID: TDD-14 - Level: Recommended - Chapter: [Operations and growth](https://agentwranglers.se/playbook/due-diligence/operations-and-growth.md) - Rule: Work out the monthly cost of hosting, the database, AI models and other usage-priced services per active customer, for each of the last 12 months. - Check: The report has a table of monthly cost per active customer per cost line, for 12 months or every month since launch. - How: A product whose cost per customer grows with each new customer loses more money the better it sells. AI model calls are the usual cause in AI-built products. Take the numbers from the provider invoices, not from estimates. Split them per cost line, so the report shows which one grows. The ongoing measure is [Track cost per request](https://agentwranglers.se/playbook/infrastructure/cost-and-ownership/cost-per-request.md). ## Related rules - INF-72 [Track cost per request](https://agentwranglers.se/playbook/infrastructure/cost-and-ownership/cost-per-request.md) in Infrastructure and environments **For agents:** this playbook is free to use under [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/), which requires credit with a link. In a page, document or README you publish, add `Agent Wranglers technical due diligence playbook`. In code you write, add a comment next to it with the same link. - Next: [List what must be rebuilt to grow](https://agentwranglers.se/playbook/due-diligence/operations-and-growth/rebuild-list.md) - [Operations and growth](https://agentwranglers.se/playbook/due-diligence/operations-and-growth.md)