How to Rename Files with Regex: Patterns for Power Users

Regular expressions (regex) enable powerful pattern-based renaming. Here's how to use them.

What is Regex?

Regex is a pattern-matching language:

Pattern: IMG_[0-9]+\.jpg
Matches: IMG_001.jpg, IMG_5847.jpg, IMG_99999.jpg

Common Regex Patterns for File Renaming

Match Any Number

[0-9]+
Matches: 1, 42, 5847, 123456

Match Any Word Characters

\w+
Matches: photo, IMG, document2024

Match File Extension

\.[a-z]+$
Matches: .jpg, .pdf, .png

Capture Groups

(IMG)_([0-9]+)\.jpg
Captures: IMG, 5847 (separately)

Practical Regex Examples

Remove Numbers from Filenames

Pattern: [0-9]
Replace: (nothing)
Before: photo123.jpg
After: photo.jpg

Replace Underscores with Hyphens

Pattern: _
Replace: -
Before: my_file_name.pdf
After: my-file-name.pdf

Remove Camera Prefix

Pattern: ^(IMG|DSC|DSCN|DSCF)_
Replace: (nothing)
Before: IMG_5847.jpg
After: 5847.jpg

Add Date Prefix

Pattern: ^
Replace: 2025-01-06-
Before: report.pdf
After: 2025-01-06-report.pdf

Extract and Reorder

Pattern: (\w+)-(\d+)\.jpg
Replace: \$2-\$1.jpg
Before: beach-001.jpg
After: 001-beach.jpg

Tools That Support Regex

Windows - Bulk Rename Utility - Advanced Renamer - PowerShell

Mac - A Better Finder Rename - Name Mangler - Terminal

Command Line

bash
# Bash example
for f in *.jpg; do
  mv "$f" "$(echo $f | sed 's/IMG_/photo-/')"
done

When NOT to Use Regex

Regex is overkill when: - You just need descriptive names - Pattern varies too much - You're not comfortable with syntax

The Alternative: AI Renaming

Instead of writing patterns, let AI understand your files:

Regex approach:
Pattern: IMG_[0-9]+\.jpg → photo-\$1.jpg
Result: photo-5847.jpg (still meaningless)

AI approach:
Input: IMG_5847.jpg
Output: sunset-beach-hawaii.jpg (actually descriptive)

File Renamer AI gives you the power of pattern matching plus the intelligence to create meaningful names.

Try File Renamer AI - Power without complexity.