Calculating Factorial of a Number using While Loop in Java

Calculating the factorial of a number is a common task in programming. In this tutorial, we will explore how to find the factorial of a number using a while loop in Java. This step-by-step guide is designed to help new learners understand the concept, syntax, and examples of using a while loop to calculate the factorial of a number.

Understanding Factorial

Factorial of a non-negative integer is the product of all positive integers less than or equal to that number. For example, the factorial of 5 is calculated as 5 x 4 x 3 x 2 x 1 = 120.

Syntax of While Loop

The syntax for the while loop in Java is as follows:

while (condition) {
// Code block to be executed repeatedly while the condition is true
// Typically, there should be a way to modify the condition inside the loop

Implementing the Program: Step-by-Step

Let’s break down the implementation of the program into step-by-step instructions:

  • Step 1: Take an integer input for which you want to calculate the factorial.
  • Step 2: Initialize a variable fact to 1 to store the factorial value.
  • Step 3: Use a while loop with the condition num > 0 to iterate until num becomes 0.
  • Step 4: Multiply fact with num and store the result back in fact.
  • Step 5: Decrement num by 1 inside the loop.
  • Step 6: After the loop ends, print the final value of fact, which represents the factorial of the input number.

Example: Calculating Factorial

Let’s consider an example where we want to find the factorial of the number 5:

int num = 5;
int fact = 1;

while (num > 0) {
fact *= num;

System.out.println(“Factorial of ” + num + ” is: ” + fact);

The output for this example will be: “Factorial of 5 is: 120”.


By utilizing the while loop in Java, we can efficiently calculate the factorial of a given number. The program we discussed simplifies the process by iteratively multiplying the factorial value with decreasing numbers. Understanding the syntax and examples provided will enable you to implement similar logic in your Java programs effectively.

Keep practicing and exploring the possibilities of while loops in Java coding. Happy programming!