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Python Program to Count Character Frequency in a String

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

Short answer
To count character frequency in Python, loop over the string and keep a dictionary of counts: freq[ch] = freq.get(ch, 0) + 1, or simply use Counter(text).

A character frequency table answers the question "how many times does each character appear?". It is the basis of anagram checks, simple ciphers and text statistics, and it is the best beginner example of using a dictionary as a counter.

Below you will build the table by hand, see how collections.Counter shortens it, and learn how to print it in a predictable order.

InputA string such as "banana"
OutputA dictionary mapping each character to its count
ApproachWalk through the string and increase a dictionary count for each character
Time complexityO(n) time, O(k) space for k distinct characters

Approach to count character frequency step by step

  1. Start with an empty dictionary, freq = {}.
  2. Loop over each character of the string.
  3. Read the current count with freq.get(ch, 0), which gives 0 for a character not seen yet.
  4. Store the count plus one back under that character.
  5. After the loop, freq holds the answer. Dictionaries keep insertion order, so characters appear in the order they were first seen.

How the frequency code works

The key line is freq[ch] = freq.get(ch, 0) + 1. Without the default, a new character would raise a KeyError, because the key does not exist yet; dict.get() avoids that.

Spaces and punctuation are characters too. If you only care about letters, add if ch.isalpha() to the loop, and call lower() first when "A" and "a" should be counted together.

Python 
freq = {}
for ch in "banana":
    freq[ch] = freq.get(ch, 0) + 1
print(freq)





      
      
    

    
    
    

      
Other ways to get letter counts

      
Counter(text) from the collections module does the whole loop for you and adds most_common(). str.count(ch) also works, but calling it for each distinct character rescans the string every time. To print the table in a stable order, loop over sorted(freq.items()); this is the safest habit when the output must be reproducible.

      
      
      

        
        
MethodCodeWhen to use

        
Manual dictionaryfreq[ch] = freq.get(ch, 0) + 1Learning how counting works
CounterCounter(text)Everyday use, needs most_common()
str.count(){c: text.count(c) for c in set(text)}Very short strings only

      

      
    

    
    

    
    

      
Examples you can run

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

      
      

        
Build a frequency dictionary

        
Count every character, including repeated ones.

        

  

    Build a frequency dictionary
    

      
      
      
      
    

  

  
text = "programming"
freq = {}
for ch in text:
    freq[ch] = freq.get(ch, 0) + 1
print(freq)

  
  
  
  

    
      
      
    
    
  

  
Expected output{'p': 1, 'r': 2, 'o': 1, 'g': 2, 'a': 1, 'm': 2, 'i': 1, 'n': 1}




      

      
      

        
Counter and most_common

        
Counter gives the same result and ranks the characters.

        

  

    Counter and most_common
    

      
      
      
      
    

  

  
from collections import Counter

counts = Counter("mississippi")
print(dict(counts))
print(counts.most_common(2))

  
  
  
  

    
      
      
    
    
  

  
Expected output{'m': 1, 'i': 4, 's': 4, 'p': 2}
[('i', 4), ('s', 4)]




      

      
      

        
Letters only, printed in sorted order

        
Ignore spaces and punctuation, and print one line per letter.

        

  

    Letters only, printed in sorted order
    

      
      
      
      
    

  

  
text = "Hello, World!"
freq = {}
for ch in text.lower():
    if ch.isalpha():
        freq[ch] = freq.get(ch, 0) + 1
for letter, count in sorted(freq.items()):
    print(letter, count)

  
  
  
  

    
      
      
    
    
  

  
Expected outputd 1
e 1
h 1
l 3
o 2
r 1
w 1




      

      
      

        
Edge case: empty string

        
An empty string produces an empty dictionary.

        

  

    Edge case: empty string
    

      
      
      
      
    

  

  
from collections import Counter

print(dict(Counter("")))

  
  
  
  

    
      
      
    
    
  

  
Expected output{}




      

      
      

        
Interactive version

        
Read a word and print its table.

        

  

    Interactive version
    

      
      
      
      
    

  

  
word = input("Enter a word: ")
freq = {}
for ch in word:
    freq[ch] = freq.get(ch, 0) + 1
for ch, n in freq.items():
    print(f"{ch}: {n}")

  

  
  
  

    
      
      
    
    
  

  
Expected outputEnter a word: apple
a: 1
p: 2
l: 1
e: 1




      

      
    

    

    
    

      
Common mistakes

      
      

        
Incrementing a missing key

        

          
✗ Wrong
freq = {}
for ch in "abc":
    freq[ch] += 1
KeyError: 'a'

          
✓ Right
freq = {}
for ch in "abc":
    freq[ch] = freq.get(ch, 0) + 1
print(freq)

        

        
Give new keys a starting value with freq.get(ch, 0) + 1, or use Counter.

      

      
      

        
Printing a set of characters in a fixed order

        

          
✗ Wrong
print(set("hello"))
The order can change between runs because string hashing is randomised

          
✓ Right
print(sorted(set("hello")))

        

        
Use sorted() when output order matters.

      

      
    

    

    
    

      
Python Program to Count Character Frequency in a String: questions people ask

      
How do I count the frequency of characters in a string in Python?
Use collections.Counter(text), or loop and update a dictionary with freq[ch] = freq.get(ch, 0) + 1.
How do I find the most frequent character?
Call Counter(text).most_common(1), which returns a list with the character and its count. With ties, the character seen first comes first.
Should spaces be counted?
Only if you want them. Spaces are ordinary characters, so skip them with if ch != " " or keep only letters with ch.isalpha().

    

    

    
    

      
Keep learning

      
Step-by-step lessons:
Python DictionariesPython collections ModulePython for Loops

      
Related:
Python Word Count Program: Count Words in a StringPython Program to Count Vowels in a StringPython Anagram Program: Check if Two Strings Are AnagramsPython Dictionary get() MethodPython String count() Method

      
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Python Program to Check Palindrome (String and Number)Python Program to Count Vowels in a StringPython Anagram Program: Check if Two Strings Are AnagramsPython Word Count Program: Count Words in a String See all →