How to Pad a String to a Fixed Length with Spaces in Python

Padding strings is useful for formatting data, aligning text, or preparing strings for output. The simplest and most common way to pad a string in Python is by using the built-in ljust() and rjust() methods.

Using ljust() and rjust() Methods

These methods add spaces to the left or right of the string until the string reaches a specific length.

Example of ljust() (pads to the right or left justified string)

a = "hello"

# Pads 'hello' to the right with spaces
ans = a.ljust(10)  
print(ans)

hello     

Example of rjust() (pads to the left or right justified string)

a = "hello"

# Pads 'hello' to the left with spaces
result = a.rjust(10) 
print(result)

     hello

These methods are fast and ideal for simple string padding tasks in Python. Other methods that we can use to pad a string to fixed length with spaces in python are:

Using center() method

The center() method in Python pads a string to the specified length by adding spaces (or any other character) to both sides of the string. This method is particularly useful when you need to center-align text or data.

a = "Hello"

# Pads the string to a total length of 10 with spaces on both 
padded_a = a.center(10)
print(f"'{padded_a}'")

'  Hello   '

Using format() method

The format() method in Python provides another way to pad strings. It’s more flexible than the previous methods and works well if we need to format numbers or strings in specific ways.

a = "hello"

# Pads to the right, making it 10 characters long
result = "{:<10}".format(a)  
print(result) 

hello     

• "{:<10}" specifies that the string should be left-aligned and padded with spaces to make the total length 10 characters.
• We can also use {:>10} to pad the string to the left.

Using f-strings

When we are using Python 3.6 or newer, f-strings are a concise and easy-to-read way to pad strings. They allow us to specify the length directly in the f-string.

a = "hello"

 # Pads to the right, making it 10 characters long
result = f"{a:<10}" 
print(result) 

hello     

• The f"{a:<10}" f-string pads the string a to the right with spaces until it reaches 10 characters.
• You can change the alignment by using {:>10} for padding to the left.