# C Program To Calculate Compound Interest

In this post, we will learn how to calculate compound interest using the C Programming language.

Compound Interest is the interest on a deposit calculated based on both the initial principal and the accumulated interest from previous periods.

Compound Interest = Total amount of principal and interest in future less principal amount at present.

CI  = [Principal * (1 + Rate of Interest)Time Period] – Principal

We will be using the same formula in our program to calculate the compound interest.

So, without further ado, let’s begin the tutorial.

## C Program To Calculate Compound Interest

```// C Program To Calculate Compound Interest
#include <stdio.h>
#include <math.h>

int main(){
float principal, rate, time, CI, amount;

printf("Enter The Principal Amount: \n");
scanf("%f", &principal);
printf("Enter Rate of Interest: \n");
scanf("%f", &rate);
printf("Enter Time Period: \n");
scanf("%f", &time);

amount = principal * (pow((1 + rate/100), time));
CI = amount - principal;
printf("Compound Interest is %.2f", CI);

return 0;
}
```

Output

``````Enter The Principal Amount:
5000
Enter Rate of Interest:
10
Enter Time Period:
3
Compound Interest is 1655.00
``````

## How Does This Program Work ?

``````    float principal, rate, time, CI, amount;
``````

In this program, we have declared five float data type variables named as principal, rate, time, CI and amount.

``````    // Asking for Input
printf("Enter The Principal Amount: \n");
scanf("%f", &principal);
printf("Enter Rate of Interest: \n");
scanf("%f", &rate);
printf("Enter Time Period: \n");
scanf("%f", &time);
``````

Then, the user is asked to enter the value of each constraint. For example: the principal amount, rate of interest and time period.

``````    amount = principal * (pow((1 + rate/100), time));
``````

Now, we used the above formula to compute the compound interest.

The pow() function is used to calculate the power raised to the base value. It is declared in the math.h header file.

``````    CI = amount - principal;
printf("Compound Interest is %.2f", CI);
``````

Then, we subtract the principal amount from the final amount to get the Compound Interest or CI.

Finally, the result is displayed to the screen using printf() function. Here, we have used %.2f format specifier because we want the result to be shown till 2 decimal places only.

## Conclusion

I hope after going through this tutorial, you understand how to calculate compound interest using C Programming language.

If you have any doubt regarding the program, feel free to contact us in the comment section. We will be delighted to help you.