C++ program to calculate simple interest and compound interest

In this tutorial, we will learn how we can calculate simple interest and compound interest using the C++ program. So let’s know what simple interest and compound interest are along with formulas.


It can be calculated on the given principal, rate, and time or we can say the original amount of the loan.


S.I = P*R*T/100

where P= principal , R = Rate , T=Time


It is used to when we want to calculate on the principal amount and the accumulated amount there previously. So it is also called interest on interest.


p*pow(1+r/100),t )-p

C++ code to calculate simple interest and compound interest

Below is the example of code to calculate simple and compound interest:

#include <iostream>
#include <conio>
#include <math.h>

using namespace std;

int main() {
 float p,r , t , si , ci;
 p = 1000;
 r = 5;
 t = 3;
 si = (p*r*t)/100;
 ci = p*pow(1+r/100),t )-p;
 cout<<"simple interest is "<<si;
 cout<<"compound interest is "<<ci
 return 0;


simple interest is 1150
compound interest is 1158

Explanation to the code

First, we will put header file math.h so as to import all necessary header files required. Then we will put float p,r,t,si,ci so that these values can take decimal values as well. After that, we will put values p,r,t in the code and write the formulas of simple interest and compound interest. Then the output will be printed on the screen using cout.

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