Loan-to-value (LTV) ratio is a fundamental underwriting metric that expresses how much of a property's value is covered by the mortgage. An 80% LTV means the borrower is putting 20% down. Lower LTV ratios represent less risk for lenders and typically result in better interest rates and terms. For investment properties, most lenders cap LTV at 75-80%, though hard money and bridge lenders may go as low as 60-70%. Understanding LTV is critical for investors because it directly affects how much capital they need to bring to each deal.