Python 3 reference · String Methods

Python String isupper() Method

Return True if all cased characters are upper case and there is at least one cased character.

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Syntax

str.isupper()

True or False.

Basic useTry it yourself

print("NASA".isupper(), "NASA 2026".isupper(), "Nasa".isupper(), "2026".isupper())

Output

True True False False

Find acronymsTry it yourself

words = "Read the FAQ before you ask the CEO".split()
print([w for w in words if w.isupper()])

Output

['FAQ', 'CEO']

Version	Change
Python 3.0	Added

str.islower() · Return True if all cased characters are lower case and there is at least one cased character.
str.upper() · Return a copy of the string with all cased characters converted to upper case.
str.istitle() · Return True if the string is title-cased: each word starts with an upper-case letter followed by lower-case letters.
Python Strings · tutorial