Java Convert Octal to Decimal

Last Updated : 17 Feb 2026

We can convert octal to decimal in java using Integer.parseInt() method or custom logic.

Java Octal to Decimal conversion: Integer.parseInt()

The Integer.parseInt() method converts a string to an int with the given radix. If you pass 8 as a radix, it converts an octal string into decimal. Let us see the signature of parseInt() method:

Let's see the simple example of converting octal to decimal in java.

//Java Program to demonstrate the use of Integer.parseInt() method
//for converting Octal to Decimal number
public class OctalToDecimalExample1{
public static void main(String args[]){
//Declaring an octal number
String octalString="121";
//Converting octal number into decimal
int decimal=Integer.parseInt(octalString,8);
//Printing converted decimal number
System.out.println(decimal);
}}

Output:

Let's see another example of Integer.parseInt() method.

//Shorthand example of Integer.parseInt() method
public class OctalToDecimalExample2{
public static void main(String args[]){
System.out.println(Integer.parseInt("121",8));
System.out.println(Integer.parseInt("23",8));
System.out.println(Integer.parseInt("10",8));
}}

Output:

81
19
8

Java Octal to Decimal conversion: Custom Logic

We can convert octal to decimal in java using custom logic.

//Java Program to demonstrate the conversion of Octal to Decimal
//using custom code
public class OctalToDecimalExample3{
//Declaring method
public static int getDecimal(int octal){  
    //Declaring variable to store decimal number
    int decimal = 0;  
    //Declaring variable to use in power
    int n = 0;  
    //writing logic 
    while(true){  
      if(octal == 0){  
        break;  
      } else {  
          int temp = octal%10;  
          decimal += temp*Math.pow(8, n);  
          octal = octal/10;  
          n++;  
       }  
    }  
    return decimal;  
}  
public static void main(String args[]){    
//Printing the result of conversion
System.out.println("Decimal of 121 octal is: "+getDecimal(121));  
System.out.println("Decimal of 23 octal is: "+getDecimal(23));  
System.out.println("Decimal of 10 octal is: "+getDecimal(10));  
}}

Output:

Decimal of 121 is: 81
Decimal of 23: 19
Decimal of 10 is: 8

References

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