

Scenario 1: Find the Monthly Payment 


Interest rate R% is always a yearly figure. However, in most loan situations it is compounded monthly. In this calculator
the monthly payment is calculated by the following formula where r = R/1200:

Scenario 2: Find the Interest Rate 


For given C, P and N, one can only solve the following equation for r by numerical means.
Given the rather smooth behavior of this equation, this calculator employs the NewtonRaphson method with an educated initial guess:

Scenario 3: Find the Number of Payments 


This calculator figures out the number of months N by the following closedform expression:
Notice that N has to be an integer, so the monthly payment P might be slightly adjusted to satisfy this condition.

