Count Files by Extension in Python

Count files in a directory grouped by file extension using Python's standard library.

Easy Python 3.9+ Aug 9, 2026 Files & data 14 views 0 copies

files pathlib directory counting extensions

Python code

16 lines

Python 3.9+

from pathlib import Path

def count_files_by_extension(directory: str) -> dict[str, int]:
    """Count files in a directory grouped by file extension."""
    data = {}
    for path in Path(directory).iterdir():
        if path.is_file():
            ext = path.suffix.lower() or "(no extension)"
            data[ext] = data.get(ext, 0) + 1
    return data

if __name__ == "__main__":
    result = count_files_by_extension(".")
    for ext, count in sorted(result.items()):
        print(f"{ext}: {count}")
    print(f"\nTotal files: {sum(result.values())}")

Output

stdout

.py: 3
.txt: 2
(no extension): 1

Total files: 6

How it works

The function uses Path.iterdir() to iterate over all entries in the directory. For each entry that is a file, it extracts the lowercase suffix (extension) and updates the count in the dictionary using get with a default of 0, avoiding KeyErrors. This approach handles files without extensions by labeling them as (no extension). The final output uses sorted to display extensions in alphabetical order.

Common mistakes

Using `path.is_file()` without checking for permission errors on some files.
Forgetting to lowercase the suffix, causing case-sensitive counts like `.PY` vs `.py`.
Using `path.suffix` on directories, which returns an empty string and adds a false `(no extension)` entry.

Variations

Use `os.listdir()` and `os.path.isfile()` for a simpler but less modern approach.
Use a `defaultdict(int)` to avoid explicit `get` calls.

Real-world use cases

Inventorying project files to track code vs. documentation breakdown.
Checking for stray files in a processed data directory before archival.
Generating file-type statistics for a cleanup or migration script.

Count Files by Extension in Python

Python code

Output

How it works

Common mistakes

Variations

Real-world use cases

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Python code

Output

How it works

Common mistakes

Variations

Real-world use cases

More from Files & data

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