Count vowels in a string in Python

Go through the text one character at a time and add 1 to a counter each time the character is a vowel.

The program

text = input("Enter a sentence: ")
vowels = "aeiou"

count = 0
for ch in text.lower():
    if ch in vowels:
        count += 1

print(f"Number of vowels: {count}")

Typed in this example: Programming in Python is fun. Press Run to type your own.

Enter a sentence: Programming in Python is fun
Number of vowels: 7

How it works

• ch in vowels is True when the character appears in the string "aeiou". The in operator checks whether one string is inside another.
• text.lower() turns capital letters into small ones first. Without it, a capital vowel such as the "A" in "Ada" would not be counted.
• Spaces, digits and punctuation are not in "aeiou", so they are skipped.

Count each vowel separately

A dictionary can hold one counter per vowel. Start each one at 0, then add to the right one:

text = "Grace Hopper wrote the first compiler"
counts = {"a": 0, "e": 0, "i": 0, "o": 0, "u": 0}

for ch in text.lower():
    if ch in counts:
        counts[ch] += 1

for vowel, n in counts.items():
    print(vowel, n)

a 1
e 5
i 2
o 3
u 0

ch in counts checks the keys of the dictionary, so it works the same way as ch in "aeiou".