What is a loan to value (LTV) ratio in real estate?

A loan-to-value (LTV) ratio is an equation that lenders use to assess the amount of risk associated with a home loan. LTV is calculated by dividing the total home loan amount by the appraised market value of the home. Typically, if the LTV ratio is higher than 0.8, lenders require private mortgage insurance (PMI) to offset the higher risk of default.