Difference between casefold() and lower() in Python Last Updated : 23 Jul, 2025 Comments Improve Suggest changes 5 Likes Like Report In this article, we will learn the differences between casefold() and lower() in Python. The string lower() is an in-built method in Python language. It converts all uppercase letters in a string into lowercase and then returns the string. Whereas casefold() method is an advanced version of lower() method, it converts the uppercase letter to lowercase including some special characters which are not specified in the ASCII table for example 'ß' which is a German letter and its lowercase letter is 'ss'.lower() method in PythonIn this example, we have stored a string in variable 's1' which includes uppercase letters, and converted it to lowercase using the lower() method.Syntax of lower(): string.lower()Parameters: It does not take any parameter.Returns: It returns a lowercase string of the given string. Python s1 = "GeeksForGeeks" s2 = s1.lower() print(s2) Outputgeeksforgeeks casefold() method in PythonIn this example, we have stored a German letter 'ß' in 's1' and converted it to lowercase using both methods casefold() and lower() and we can see in the output that casefold() converts it to lowercase whereas using lower(), the letter is printed as it is after conversion.Syntax of casefold(): string.casefold()Parameters: It does not take any parameter.Returns: It returns a lowercase string of the given string. Python s1 = "ß" s2 = s1.casefold() print("Using casefold() - ",s2) s3 = s1.lower() print("Using lower() - ",s3) OutputUsing casefold() - ss Using lower() - ß Difference between lower() and casefold() in PythonFeaturelower()casefold()PurposeConverts uppercase letters to lowercase.Converts uppercase letters to lowercase, including special characters and locale-specific cases.Handling of Special CharactersDoesn't handle special or language-specific cases.Handles special cases like German "ß" (sharp S) correctly (e.g., "ß".casefold() => "ss").Use CaseBasic lowercase conversion for general text processing.Best for case-insensitive comparisons, especially for multilingual text.Example"HELLO".lower() => "hello""HELLO".casefold() => "hello"Example with Special Characters"ß".lower() => "ß""ß".casefold() => "ss" Create Quiz Comment S sagar99 Follow 5 Improve S sagar99 Follow 5 Improve Article Tags : Python Python-Functions Python-Built-in-functions Explore Python FundamentalsPython Introduction 2 min read Input and Output in Python 4 min read Python Variables 4 min read Python Operators 4 min read Python Keywords 2 min read Python Data Types 8 min read Conditional Statements in Python 3 min read Loops in Python - For, While and Nested Loops 5 min read Python Functions 5 min read Recursion in Python 4 min read Python Lambda Functions 5 min read Python Data StructuresPython String 5 min read Python Lists 4 min read Python Tuples 4 min read Python Dictionary 3 min read Python Sets 6 min read Python Arrays 7 min read List Comprehension in Python 4 min read Advanced PythonPython OOP Concepts 11 min read Python Exception Handling 5 min read File Handling in Python 4 min read Python Database Tutorial 4 min read Python MongoDB Tutorial 3 min read Python MySQL 9 min read Python Packages 10 min read Python Modules 3 min read Python DSA Libraries 15 min read List of Python GUI Library and Packages 3 min read Data Science with PythonNumPy Tutorial - Python Library 3 min read Pandas Tutorial 4 min read Matplotlib Tutorial 5 min read Python Seaborn Tutorial 3 min read StatsModel Library - Tutorial 3 min read Learning Model Building in Scikit-learn 6 min read TensorFlow Tutorial 2 min read PyTorch Tutorial 6 min read Web Development with PythonFlask Tutorial 8 min read Django Tutorial | Learn Django Framework 7 min read Django ORM - Inserting, Updating & Deleting Data 4 min read Templating With Jinja2 in Flask 6 min read Django Templates 5 min read Build a REST API using Flask - Python 3 min read Building a Simple API with Django REST Framework 3 min read Python PracticePython Quiz 1 min read Python Coding Practice 1 min read Python Interview Questions and Answers 15+ min read Like