Question: what is the formula to calculate total interest on a loan in excel?
Answer: For example, you have borrowed $100000 from bank in total, the annual loan interest rate is 5.20%, and you will pay the bank every month in the coming 3 years as below screenshot shown. ... 
Select the cell you will place the calculated result in, type the formula =CUMIPMT(B2/12,B3*12,B1,B4,B5,1), and press the Enter key.