str.lower() Lowercase
Last updated: 2026-09-22
str.lower() Lowercase
str.lower() returns a lowercased copy.
| Category | String Methods |
|---|---|
| Kind | Built-in Type Method |
| Python Version | all |
📝 Syntax
str.lower()Returns：str. A copy with all letters lowercased.
Mutates the original：No (returns a new object)
▶ Example
Edit the code, press Run, and see the result in the output panel:
Output：
hello world💡 Related Cases
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❓ FAQ
QDoes lower() modify the original string?
ANo. Strings are immutable; lower() returns a new lowercase string and leaves the original unchanged.
QWhat is the difference between lower() and casefold()?
Alower() only performs ordinary lowercase conversion; casefold() is more aggressive and can handle characters such as the German ß. Use casefold() for case-insensitive comparisons to be more reliable.
QWhat happens when calling lower() on Chinese?
AChinese has no case, so it is returned unchanged. '你好'.lower() returns '你好'.
