Cost per Feature: The SQL Formula That Actually Works in Production
· 10 min read
A staff engineer asks the analytics lead a simple question: "How much did the SSO feature actually cost?" Forty minutes later, the analyst comes back with a number. It's wrong by 35%. Not because the analyst is bad, but because the SQL SUM(hours) × $50 lost the rate-type branching, missed the per-month overhead K, and treated a contractor on monthly invoice the same as a salaried engineer. McKinsey's 2023 Developer Velocity Index lands the typical engineering overhead at 30–55% of payroll; if your cost-per-feature query doesn't multiply through, you're running on the wrong half of those numbers. The fix is a real PostgreSQL query, with all three layers in it. This post is that query.