A spending leak is a recurring expense that delivers significantly less value than its cost — subscriptions you barely use, fees you could automate away, convenience premiums you pay habitually rather than deliberately, and impulse purchases that accumulate without notice. Individually, each leak appears minor. Together, they can represent 5–20% of monthly income flowing to spending that doesn't align with your actual priorities. The Spending Leak Detector identifies leaks across 15 common categories: unused subscriptions, duplicate services, banking fees, gym and membership waste, daily convenience spending, food delivery premiums, impulse purchases, wasted groceries, convenience premiums, and forgotten items never returned. For each identified leak, it calculates not just the monthly cost but the 10-year compound cost — how much that money would have grown if invested at 7% annual return instead of spent. The 10-year cost figure is consistently the most clarifying output: $95/month in unused streaming subscriptions is $1,140/year and $19,700 over 10 years. For most people, the total 10-year compound cost of their spending leaks is between $40,000 and $180,000 — money that could represent years of earlier financial freedom or a dramatically improved retirement position.