C Program to Calculate Compound Interest

In this article, we are going to learn how to calculate Compound Interest using a C language program. The Compound Interest can be calculated by using a simple formula. The formula for Compound interest is:

Formula to calculate Compound Interest

Amount = Principal(1 + Rate/Num)^(NumTime)


  • Amount: This is amount value including interest and principal.
  • Principal :This is the amount borrowed on interest.
  • Rate :This is the rate in % at which interest will be charges
  • Num : This number tells us how interest will be compounded. For example, Quarterly,Half Yearly , Annually.
  • Time : This is time for which this money is borrowed.

The Compound interest earned can be calculated with the below calculation once you have the Amount.

CompoundInterest = Amount - Principal;

C Program to Calculate Compound Interest

Now let us see this formula in action using the C program below.

int main()

     float PrincipalAmt, time, rate, num, Amount;
     printf("Please enter the Principal Amount: ");
     printf("Please enter the Rate of Interest: ");
     printf("Please enter the Time: ");
     printf("Please enter the Number of Compounding: ");

    Amount = PrincipalAmt*pow( (1+(rate/num)), (num*time));

    printf("The Amount will become : %.2f\n",Amount);

    long CompoundInterest = Amount - PrincipalAmt;

    printf("The Compound Interest Earned is : %.2f\n",CompoundInterest);

   return 0;