Bulk Image Renamer

Why filenames are the cheapest organisation you'll ever do

IMG_4821.JPG tells you nothing, and a folder of two hundred of them tells you nothing two hundred times. A good filename is metadata you can read at a glance, in any file browser, on any operating system, forever — no app required. Rename a shoot to 2026-06-19_porto-trip_012.jpg and the file is suddenly self-describing: you know when, what, and where it sits in sequence without opening it. The payoff lands months later, when you're hunting for one photo among thousands and a descriptive, consistently-named set is searchable and scannable where a wall of camera codes is a haystack.

Batch renaming exists because doing this by hand is both tedious and error-prone — rename four hundred files individually and you'll fat-finger a few, creating duplicates and gaps. A pattern applied across the whole set is consistent by construction: every file follows the same scheme, so the set sorts and filters predictably.

Patterns, sequences and the leading-zero trap

• Pattern + counter — define a base name and a running number, e.g. invoice_001, invoice_002. The base carries meaning; the counter keeps every name unique.
• Leading zeros are not optional — name files 1, 2, ... 10 and your file manager sorts them 1, 10, 11, 2, 3 because it's sorting text, not numbers. Pad to 001, 002, ... 010 and they sort correctly. Match the width to the count: three digits for hundreds, four for thousands.
• EXIF-date naming — prefix with the capture date pulled from the photo's metadata, so files order chronologically across multiple cameras and phones regardless of when they were copied off.
• ISO dates only (YYYY-MM-DD) — 2026-06-19 sorts correctly as text and is unambiguous worldwide; 06/19/26 or 19-06-2026 neither sort nor read reliably across regions.
• Find-and-replace — strip a clumsy camera prefix or swap a project code across the whole batch in one pass, without renumbering anything.

Cross-platform pitfalls and what renaming won't fix

A few characters will bite you when files move between systems. Windows forbids \ / : * ? " < > | in filenames outright, and a name that works on macOS can break a Windows copy or a cloud sync. Spaces are legal but a nuisance in URLs and scripts, so hyphens or underscores travel better. Keep names a sensible length, stick to letters, numbers, hyphens, underscores and dots, and you'll never hit a 'this file couldn't be copied' wall. For cleaning up names that already contain illegal or awkward characters, the filename cleaner is the focused tool.

Two honest boundaries. First, renaming the file changes only its name — it does not touch the pixels, the format, or the embedded EXIF, so the GPS coordinates and camera serial inside a photo survive a rename untouched. If you're renaming before posting or sharing publicly, strip that metadata separately with EXIF removal, and see the guide on cleaning files before sharing for the full pre-share checklist. Second, a rename is not a backup or a conversion: the bytes are identical, so if you also need a smaller or different format, compress or convert the files as a separate step.