Python Program for Binary To Decimal Conversion

September 28, 2022

Binary to Decimal Conversion

In this article we will discuss binary to decimal conversion in Python. For this purpose we need to take a binary integer number from user and convert that binary integer number to its decimal equivalent form and then print the converted number on to the screen. A Decimal number can be calculated by multiplying every digits of binary number with 2 to the power of the integers starts from 0 to n-1 where n refers as the total number of digits present in a binary number and finally add all of them.

Binary to decimal conversion

Working :

 A Decimal number can be calculated by multiplying every digits of binary number with 2 to the power of the integers

 starts from 0 to n-1 where n refers as the total number of digits present in a binary number and finally add all of them.

Methods Discussed :

  1. Algorithmic way (Binary to Decimal)
  2. Inbuilt Method (Binary to Decimal)

Method 1

Algorithm :

  • While num is greater then zero
  • Store the unit place value of num to a variable (rem)
  • Calculate rem with base and add it to answer
  • Completely divide Num by 10 and multiply base with 2

Time and Space Complexities

  • Time Complexity – O(N), where N is the count of the digits in the binary number
  • Space Complexity – O(1), Constant Space

Python Code :

Run 
num = 10
binary_val = num
decimal_val = 0
base = 1

while num > 0:
    rem = num % 10
    decimal_val = decimal_val + rem * base
    num = num // 10
    base = base * 2

print("Binary Number is {}\nDecimal Number is {}".format(binary_val, decimal_val))

Output :

Binary Number is 10
Decimal Number is 2

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21 comments on “Python Program for Binary To Decimal Conversion”


  • sourav

    #we also can convert any binary number to decimal with this code efficiently
    def BtoD(n):
    Sum=0
    for i in range(len(n)):
    if(int(n[i])==0 or int(n[i])==1):
    Sum=Sum + (int(n[i])*(2**(len(n)-(i+1))))
    else:
    n=input(“Enter valid binary number: “)
    return BtoD(n)
    print(Sum)

    n=input(“enter your binary number to convert in decimal number: “)
    BtoD(n)


  • sourav

    #we also can convert any binary number to decimal with this code efficiently
    def BtoD(n):
    Sum=0
    for i in range(len(n)):
    if(int(n[i])==0 or int(n[i])==1):
    Sum=Sum + (int(n[i])*(2**(len(n)-(i+1))))
    else:
    n=input(“Enter valid binary number: “)
    return BtoD(n)
    print(Sum)

    n=input(“enter your binary number to convert in decimal number: “)
    BtoD(n)


  • sarthak

    def bintodec(num) :
    n = len(str(num))
    sum = 0

    for i in str(num) :
    sum =sum + int(i) * 2**(n-1)
    n -= 1
    return sum
    num = int(input(“enter the binary number”))

    res = bintodec(num)

    print(res)


  • 121910307021

    I THINK THE ABOVE PROGRAM BY @SHUBHANSHU ARYA IS WRONG BECAUSE IT IS EVEN ACCEPTING IF WE GIVE NUMBERS IN 2,3,4…
    SO MY CODE IS:
    def bintodec(n):
    sum= 0
    x=1
    while(n>0):
    r=n%10
    if(r==0):
    sum=sum+pow(x,0)
    x = x*2
    n=n//10
    elif(r==1):
    sum=sum+pow(x,1)
    x=x*2
    n=n//10
    else:
    print(“invalid input”)
    break

    return sum

    n=int(input(“enter number”))
    print(“DECIMAL OF {} IS BINARY OF {}”.format(bintodec(n), n))


  • Mansi

    #decimal to binary
    N=int(input())
    string=str (N)
    arr=[]
    for i in (string):
    arr.append(int(i))
    l=len(arr)
    s=0
    j=l-1
    while j>=0:

    for i in range(0,l,1):
    s=s+ ((2**i) * arr[j])
    j=j-1
    print(s)


  • Sonal

    num1=int(input(“Enter the 1st number “))
    sum=0
    temp=num1
    base=1
    while(temp):
    digit=temp%10
    sum+=digit*(base)
    temp//=10
    base*=2
    print(“{} is the decimal number of {}”.format(sum,num1))


  • dileep

    num1 = int(input(“Enter a value 0 or 1:”))
    num2 = int(input(“Enter a value 0 or 1:”))
    num3 = int(input(“Enter a value 0 or 1:”))
    num4 = int(input(“Enter a value 0 or 1:”))
    binary= ((2**0)*num4+(2**1)*num3+(2**2)*num2+(2**3)*num1)
    print(“the decimal no. for given binary is {} “.format(binary))


  • Arun

    a=input(“enter the value :”)
    c=0
    for x in range(len(a)):
    b=int(a[-1-x])*pow(2,int(x))
    c=c+b
    print(c)


  • Abhishek

    num =input(“Enter The Binary Number:”)
    n=(num)
    x=n[::-1]
    sum=0
    for i in range(0,len(x)):
    a=int(x[i])*2**i
    sum=sum+int(a)
    print(“The Decimal No is=”,sum)


  • gaurav

    import math
    a = input(“Enter binary number: “)
    k = len(a)
    decimal = 0
    for i in range(0,k):
    if int(a[(k-1)-i]) == 1:
    decimal= decimal + pow(2,i)
    print(“decimal: “, decimal)


  • Souvik

    raw = input()

    l = len(raw)
    dec = 0
    for i in range(l):
    dec += int(raw[i])*(2**(l-i-1))

    print(dec)

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