How to Count Occurrences in a List in Python
my_list.count(item) to count one item, or collections.Counter(my_list) to count every item in a single pass. Counter(my_list).most_common(3) gives the three most frequent values.Counting how often something appears answers questions like "how many orders for each product?" or "which word is used most?". For one value the count() method is perfect. For many values it becomes slow, because each call scans the whole list again, and Counter is the better tool.
Both are standard Python, no installation needed. See also the list method reference and the collections module.
| One item | my_list.count(item) |
|---|---|
| All items | Counter(my_list) from collections |
| Most common | Counter(my_list).most_common(n) |
| Missing item | Returns 0, no error |
| Time complexity | count() O(n) per call; Counter O(n) once |
Count one item with list.count()
list.count() scans the list and returns how many items are equal to the value you give it. If the value is not present, it returns 0.
votes = ["red", "blue", "red", "green", "red"]
print(votes.count("red"))
print(votes.count("pink"))Count every item at once with collections.Counter
Counter reads the list one time and builds a dictionary-like object mapping each item to its count. Looking up a missing item gives 0. Convert it with dict() if you want a normal dictionary.
from collections import Counter
votes = ["red", "blue", "red", "green", "red"]
counts = Counter(votes)
print(dict(counts))
print(counts["red"])Find the most common items with most_common()
most_common(n) returns a list of (item, count) pairs ordered from highest to lowest count. Items with equal counts keep the order in which they first appeared in the list.
from collections import Counter
words = ["a", "b", "a", "c", "b", "a"]
print(Counter(words).most_common(2))Count with a plain dictionary loop
If you cannot import Counter, or want to learn how it works, count with a dictionary and get(). Each item starts at 0 and goes up by one every time you see it.
counts = {}
for item in ["a", "b", "a"]:
counts[item] = counts.get(item, 0) + 1
print(counts) # {'a': 2, 'b': 1}Counting methods compared
| Method | Counts | Best for | Repeated lookups |
|---|---|---|---|
lst.count(x) | One value | A single question | Slow (rescans) |
Counter(lst) | All values | Frequency tables | Fast |
| Dictionary loop | All values | Learning, custom rules | Fast |
sum(1 for x in lst if cond) | Items matching a condition | Counting with a test | Rescans each time |
Examples you can run
Press Run, then edit the code and run it again.
Count one value
count() returns 0 for items that are not in the list.
orders = ["pen", "book", "pen", "ink", "pen"]
print(orders.count("pen"))
print(orders.count("glue"))Expected output3
0
Count everything with Counter
Printing dict(counts) shows a plain dictionary in first-seen order.
from collections import Counter
orders = ["pen", "book", "pen", "ink", "pen"]
counts = Counter(orders)
print(dict(counts))
print(counts["glue"])Expected output{'pen': 3, 'book': 1, 'ink': 1}
0
Top two most common values
most_common() sorts by count, highest first.
from collections import Counter
words = "to be or not to be to go".split()
print(Counter(words).most_common(2))Expected output[('to', 3), ('be', 2)]
Count items that match a condition
A generator expression with sum() counts how many values pass a test.
scores = [45, 82, 67, 91, 38, 76]
passed = sum(1 for s in scores if s >= 50)
print(passed)Expected output4
Common mistakes
Calling count() inside a loop over a big list
✗ Wrong
data = [1, 2, 1, 3] * 1000
for x in set(data):
print(x, data.count(x))✓ Right
from collections import Counter
data = [1, 2, 1, 3] * 1000
for x, n in Counter(data).items():
print(x, n)Build a Counter once and look up the counts.
Passing several values to count()
✗ Wrong
nums = [1, 2, 1, 3]
print(nums.count(1, 3))✓ Right
nums = [1, 2, 1, 3]
print(nums.count(1) + nums.count(3))count() accepts one value. Use Counter for several or sum the individual counts.
Mixing up case in strings
✗ Wrong
names = ["Asha", "asha", "ASHA"]
print(names.count("asha"))✓ Right
names = ["Asha", "asha", "ASHA"]
print([n.lower() for n in names].count("asha"))count() compares exactly. Normalize with lower() first.
How to Count Occurrences in a List in Python: questions people ask
How do I count occurrences of an element in a list in Python?
Call my_list.count(element). It returns the number of items equal to element, or 0 if there are none.
How do I count all elements in a list at once?
Use collections.Counter(my_list), which returns each item with its count after a single pass through the list.
How do I find the most frequent element in a list?
Use Counter(my_list).most_common(1), which returns a list with one (item, count) pair. Take [0][0] for just the item.
Keep learning
Step-by-step lessons:
Python List MethodsPython collections ModulePython Dictionaries
Related:
Python List count() MethodPython Program to Count Character Frequency in a StringPython Word Count Program: Count Words in a StringHow to Remove Duplicates from a List in PythonPython String count() Method
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