Loan Calculator Formula & How It Works
- M = Monthly payment
- P = Principal (loan amount)
- r = Monthly interest rate = Annual Rate ÷ 12 ÷ 100
- n = Total number of monthly payments
This standard loan amortization formula computes a fixed monthly payment that covers both interest on the remaining balance and principal repayment. Total interest paid = (M × n) − P. The same formula applies to mortgages, car loans, student loans, and personal loans.