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Artem Divertitto
Senior Android Developer at United Tech

Java Convert Binary to Decimal

Published in the Java Numbers group

Binary to Decimal conversion in Java

Numbers that have only 2 digits, 0 and 1, are called binary numbers. They are expressed only in the base 2 number system. We know that the binary system is the native digital language of modern computers. But we are more accustomed to decimal numbers. Of course, you can convert binary numbers to decimal and vice versa. On the diagram below you can see an example binary to decimal conversion. 10101 is a binary number used to explain mathematical calculations. Java Convert Binary to Decimal - 1We just need to follow the 3 simple steps. Always take the digit from the right side of a binary number, multiply it with the power of 2 and then simply add them. You’ll get the decimal number that is 21 in this case. There are two ways for converting binary to decimal in java.
  1. Using Java method
  2. Using custom logic

Java Prebuilt Method

Java provides us with the Integer.parseInt() method to convert the string into an integer. parseInt() method belongs to the Integer class.


public static int parseInt(String binaryNumber, int radix)


public class ConvertingBinaryToDecimal {
    public static void main(String args[]){
        String binaryNumber="10101";
        int decimalNumber=Integer.parseInt(binaryNumber,2);



Using Custom Logic

We can also write a program in Java that receives an integer and converts it to a decimal number. Let’s look at an example to understand it.


public class ConvertingBinaryToDecimal {
    // function for converting binary to decimal number
    public static int getDecimalNumber(int binaryNumber){
        int decimalNumber = 0;
        int power = 0;
        while(binaryNumber > 0){
            //taking the rightmost digit from binaryNumber
            int temp = binaryNumber%10;
            //now multiplying the digit and adding it to decimalNumber variable
            decimalNumber += temp*Math.pow(2, power);
            //removing the rightmost digit from binaryNumber variable
            binaryNumber = binaryNumber/10;
            //incrementing the power variable by 1 to be used as power for 2
        return decimalNumber;

    public static void main(String args[]){
        System.out.println("Decimal value is: "+getDecimalNumber(111010));
        System.out.println("Decimal value is: "+getDecimalNumber(001010));


Decimal value is: 58 Decimal value is: 24


We hope by now you understand how to convert binary to decimal in java. Feel free to practice and get back whenever you need more assistance. Happy learning!
Comments (2)
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matemate123 Level 50, Kraków, Poland
26 January 2023
Amazing and simple algoritm. Moreover I didn't knew that parseInt method can takes two arguments and convert binary to decimal so fast. Short but so helpful article, mandatory save in bookmarks for later needs