This basic mortgage calculator finds the monthly payment based on three input variables: amount of the loan (home cost - down payment), annual percentage rate of the loan (APR), and the length of the loan in years. Thanks to Hugh Chou for the formula below:

p = loan amount (principal)

i = APR / 12 / 100

m = length of loan in months

monthly payment = p * i / (1 - (1 + i)^-m)

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Mortgage Calculator