Formula Used
Monthly payment = P × [r(1 + r)^n] ÷ [(1 + r)^n − 1]
P = principal, r = periodic interest rate, n = number of payments.
How the formula is applied
The calculation links Current home value ($), Mortgage balance ($) and Interest rate (%) to available home equity. An equity amount and a borrowing limit are different: a lender may allow financing only up to a share of property value after existing loans.