Now, I want to calculate the loan amount so that my monthly payment is $1,000. I use the following PMT formula in cell B4 to calculate the Monthly payment: =PMT(B2/12,B3,B1) Goal Seek in Excel, as the name suggests, helps you in achieving a value (the goal) by altering a dependent value.įor example, I have the data (as shown below), where I calculate the Monthly payment outflow with the given Loan Amount, Interest Rate and Number of Payments.