In this video, you'll learn about loan-to-value ratios. A low-to-value (LTV) ratio is ratio that financial institutions and other lenders use to calculate lending risk before approving a mortgage. LTV ratios determine whether a lender will extend credit to a borrower and how much the down payment should be. If the LTV ratio is at or below 80 percent, most lenders will offer the borrower the lowest possible interest rate. Watch this video to see exactly how loan-to-value ratios are calculated.