Python String replace() Method

Q: Does replace() change the original string in Python?

No. Strings are immutable, so `replace()` returns a new string and the original is unchanged.

Q: How do I replace only the first occurrence of a character in a string?

Pass a count of 1: `text.replace("a", "b", 1)`.

Q: How do I replace multiple different characters in a string?

Chain several `replace()` calls, or use `str.translate()` for single characters or `re.sub()` for patterns.

By Yogesh Sharma (LinkedIn) · Every code example is run and checked on Python 3.13 (how we test) · Last updated 21 Oct 2026

Short answer

text.replace(old, new, count=-1) returns a new string in which every occurrence of old is replaced by new, or only the first count occurrences if you give a count.

replace() is the simplest way to fix text: change a word, remove unwanted characters, or swap a separator. It searches for an exact, case-sensitive substring, so it is not a pattern matcher; for patterns use the regex module.

Because strings are immutable, the original text stays as it was. You must save the returned string if you want to keep the change.

Quick facts
Syntax	`text.replace(old, new, count=-1)`
Parameters	`old`: substring to find; `new`: replacement; `count` (optional): maximum number of replacements
Returns	A new `str`
Time complexity	O(n) in the length of the string

How replace() finds and swaps substrings

Python scans from left to right, and each match is replaced by new. Matches do not overlap. The search is case-sensitive, so "Cat" does not match "cat". If old is not found, you get back an equal copy of the string with no error.

Python

sentence = "cats chase cats"
print(sentence.replace("cats", "dogs"))
print(sentence.replace("Cats", "dogs"))

Replacing only the first few matches with count

The optional third argument limits how many replacements happen, counting from the left. Pass it as a positional argument or as count= (keyword form is supported since Python 3.13). A count of 0 makes no replacement.

Python

text = "a-b-c-d"
print(text.replace("-", "+", 1))
print(text.replace("-", "+", 2))
print(text.replace("-", ""))

Replacing with an empty string, as in the last line, deletes the match.

replace() vs translate() vs re.sub()

Tool	Best for	Case-insensitive?	Example
`replace()`	One exact substring	No	`s.replace("a", "b")`
Chained `replace()`	A few different substrings	No	`s.replace("a", "b").replace("c", "d")`
`str.translate()`	Many single-character swaps at once	No	`s.translate(table)`
`re.sub()`	Patterns, optional flags	Yes, with `re.IGNORECASE`	`re.sub(r"\d+", "#", s)`
Slicing + concatenation	Replacing by position	Not applicable	`s[:2] + "X" + s[3:]`

Common uses: cleaning and formatting text

Typical jobs are removing spaces (replace(" ", "")), turning a title into a slug (replace(" ", "-")), or masking a character. When you need several replacements, chain the calls; they run in order, so later calls see the output of earlier ones. See removing whitespace from a string for the full set of options.

Examples you can run

Press Run, then edit the code and run it again.

Replace a word everywhere

All matches are replaced.

Replace a word everywhere

message = "Hello, world! Hello, Python!"
print(message.replace("Hello", "Hi"))

Expected outputHi, world! Hi, Python!

Limit the replacements with count

Only the first match changes.

Limit the replacements with count

path = "a/b/c/d"
print(path.replace("/", "\\", 1))
print(path.replace("/", " > "))

Expected outputa\b/c/d
a > b > c > d

Chain replace() calls to build a slug

Each call works on the result of the previous one.

Chain replace() calls to build a slug

title = "Learn Python: Strings & Lists"
slug = title.lower().replace(":", "").replace("&", "and").replace(" ", "-")
print(slug)

Expected outputlearn-python-strings-and-lists

Common mistakes

Expecting the original string to change

✗ Wrong

name = "Asha Rao"
name.replace("Asha", "Ravi")
print(name)

Asha Rao (unchanged)

✓ Right

name = "Asha Rao"
name = name.replace("Asha", "Ravi")
print(name)

Assign the result back to a variable.

Forgetting that matching is case-sensitive

✗ Wrong

print("Red red RED".replace("red", "blue"))

Red blue RED (only the exact lower-case match changed)

✓ Right

import re
print(re.sub("red", "blue", "Red red RED", flags=re.IGNORECASE))

Normalise the case first, or use re.sub() with re.IGNORECASE.

Replacing inside words by accident

✗ Wrong

print("cat concatenate".replace("cat", "dog"))

dog condogenate

✓ Right

import re
print(re.sub(r"\bcat\b", "dog", "cat concatenate"))

replace() ignores word boundaries. Use re.sub(r"\bcat\b", ...) to match whole words.

Python String replace() Method: questions people ask

Does replace() change the original string in Python?

No. Strings are immutable, so replace() returns a new string and the original is unchanged.

How do I replace only the first occurrence of a character in a string?

Pass a count of 1: text.replace("a", "b", 1).

How do I replace multiple different characters in a string?

Chain several replace() calls, or use str.translate() for single characters or re.sub() for patterns.

Keep learning

Step-by-step lessons:
Python Strings Python String Methods

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