🚀 Day 101/150 – Password Strength Checker in Python

A strong password helps protect your accounts from unauthorized access. A good password should contain a mix of uppercase letters, lowercase letters, numbers, and special characters, and it should be at least 8 characters long.

In this post, we'll explore four different ways to check password strength in Python.

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Method 1 – Check Password Length

The simplest way to check whether a password is strong is by verifying its length.

password = input("Enter your password: ")

if len(password) >= 8:
    print("Strong Password")
else:
    print("Weak Password")

Sample Input

python123

Output

Strong Password

Explanation

• input() reads the password entered by the user.

• len() calculates the password length.

• If the length is 8 or more, the password is considered strong.

• Otherwise, it is considered weak.

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Method 2 – Check for Uppercase, Lowercase, and Digits

Verify that the password contains different types of characters.

password = input("Enter your password: ")

has_upper = any(char.isupper() for char in password)
has_lower = any(char.islower() for char in password)
has_digit = any(char.isdigit() for char in password)

if has_upper and has_lower and has_digit:
    print("Strong Password")
else:
    print("Weak Password")









Sample Input

Python123

Output

Strong Password

Explanation

• isupper() checks for uppercase letters.

• islower() checks for lowercase letters.

• isdigit() checks for numeric digits.

• any() returns True if at least one matching character is found.

• The password is strong only if all three conditions are satisfied.

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Method 3 – Check for Special Characters

Require the password to include at least one special character.

password = input("Enter your password: ")

special = "!@#$%^&*()_+-=[]{}|;:',.<>?/"

has_special = any(char in special for char in password)

if has_special:
    print("Password contains a special character.")
else:
    print("Password needs a special character.")









Sample Input

Python@123

Output

Password contains a special character.

Explanation

• A string of allowed special characters is created.

• The program checks whether any character in the password belongs to that string.

• A password with at least one special character is generally more secure.

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Method 4 – Complete Password Strength Checker

Combine all the checks into a single program.

password = input("Enter your password: ")

special = "!@#$%^&*()_+-=[]{}|;:',.<>?/"

if (len(password) >= 8 and
    any(char.isupper() for char in password) and
    any(char.islower() for char in password) and
    any(char.isdigit() for char in password) and
    any(char in special for char in password)):
    print("Strong Password")
else:
    print("Weak Password")

Sample Input

Python@123

Output

Strong Password

Explanation

• The password must be at least 8 characters long.

• It must contain:

  • At least one uppercase letter.

  • At least one lowercase letter.

  • At least one digit.

  • At least one special character.

• If all conditions are met, the password is considered strong.

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Comparison of Methods

Method	Best For
Check Length	Basic password validation
Character Type Check	Checking letters and numbers
Special Character Check	Improving password security
Complete Password Checker	Real-world password validation

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🔥 Key Takeaways

• A strong password should be at least 8 characters long.

• Include uppercase letters, lowercase letters, digits, and special characters.

• Functions like isupper(), islower(), isdigit(), and any() make password validation simple.

• Combining multiple checks provides better password security.

• Password strength checkers are commonly used in login and registration systems.

Stay tuned for Day 102 of the #150DaysOfPython series! 🚀