When you work with loans with constant principal repayments, you have to know the amount of the principal repayments ( A_s ), dividing the principal ( C₀ ) by the number of periods:

Once calulated the principal repayments ( A_s ), you have to calculate the amortization payments ( a_s ) with the following formula:

Now, you have to calculate the interest payments ( I_s ) of each period with the following formula:

The only thing that need be considered is to always work with the effective rate of interest per time unit ( i^(m) ), because of that, if you do not enter this rate of interest, it is necessary to do the following conversion: