The amount of equity available for a home equity loan or home equity line of credit is determined by the loan-to-value ratio of the home and the ratio requirements of the lender. A loan-to-value ratio is calculated by taking total mortgage debt (including any second mortgages or existing home equity loans) and dividing it by the current, appraised value of the home. The size of a home equity loan or line of credit will also depend on the loan-to-value requirements of the lender. Higher loan-to-value requirements can result in larger home equity loans or lines of credit.