How to get a string left padded with zeros in Python?

String padding is commonly needed when formatting numbers, creating fixed-width output, or aligning text. Python provides several built-in methods to left-pad strings with zeros: rjust(), format(), zfill(), and f-string formatting.

Using rjust() Method

The rjust() method right-justifies a string by padding it with a specified character on the left. It takes two parameters: the total width and the fill character (default is space).

Syntax

string.rjust(width, fillchar)

Example

text = "Welcome to Tutorialspoint"
padded = text.rjust(30, '0')

print("Original string:", text)
print("Padded string:", padded)
print("Length:", len(padded))

Original string: Welcome to Tutorialspoint
Padded string: 00000Welcome to Tutorialspoint
Length: 30

Using format() Method

The format() method uses format specifiers to control padding. Use {:0>width} where 0 is the fill character, > means right-align (left-pad), and width is the total width.

Example

text = "Python"
padded = '{:0>10}'.format(text)

print("Original string:", text)
print("Padded string:", padded)

Original string: Python
Padded string: 0000Python

Using zfill() Method

The zfill() method is specifically designed for zero-padding strings. It's the most straightforward approach when you only need to pad with zeros.

Example

text = "123"
padded = text.zfill(8)

print("Original string:", text)
print("Padded string:", padded)

# Works well with numbers
number = "42"
padded_number = number.zfill(5)
print("Padded number:", padded_number)

Original string: 123
Padded string: 00000123
Padded number: 00042

Using f-string Formatting

F-strings (Python 3.6+) provide a modern way to format strings with zero-padding using the same format specifiers as format().

Example

text = "Hello"
width = 12
padded = f'{text:0>{width}}'

print("Original string:", text)
print("Padded string:", padded)

# Dynamic width
for w in [8, 10, 15]:
    print(f"Width {w}: {text:0>{w}}")

Original string: Hello
Padded string: 0000000Hello
Width 8: 000Hello
Width 10: 00000Hello
Width 15: 0000000000Hello

Comparison

Conclusion

Use zfill() for simple zero-padding, rjust() for other fill characters, and f-strings for modern, readable formatting. All methods handle edge cases where the string is already longer than the specified width.