Plan for 3-6 months of operating expenses as working capital. This typically means $20,000-$50,000 for a food truck, $50,000-$150,000 for fast casual, and $100,000-$300,000 for full-service restaurants. Working capital covers rent, payroll, utilities, inventory, and unexpected expenses while you build sales volume. Many restaurants fail not because of a bad concept, but because they run out of cash before becoming profitable.