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Naming files properly: dates, characters and the 260-character trap

Why a date in a file name has to start with the year, which characters cause trouble, and how to rename hundreds of files at once.

A good file name saves more time than any folder structure. It says in one line what is inside and when it came about – and it sorts itself into the right place. Three rules are enough for that.

The date starts with the year

The single most important rule: write the date as year-month-day, with leading zeros. So “2026-03-14”, not “14/03/2026” and certainly not “14-3-26”.

2026-03-14 City Utilities annual statement.pdf

The reason is simple: in this form, alphabetical sorting is chronological sorting. Every file manager on every operating system puts the files in the right order by itself – without you turning on a column or changing a sort setting.

With “14/03/2026” the opposite happens: 14 March ends up next to 14 July and 14 November, and the year stops mattering entirely. The format is not a matter of taste, by the way – it is a standard, ISO 8601.

Characters that cause trouble

Windows flatly forbids a few characters, because they carry their own meaning in the file system:

\  /  :  *  ?  "  <  >  |

Others are allowed but cause difficulties later. Accented characters work perfectly on your own machine but turn into garbled text in some cloud services, in links and on older systems. If you pass files on to other people, plain ASCII is the quieter choice.

Spaces are harmless as long as the file stays on your computer. The moment it appears in a link, every space becomes “%20”. For anything headed to the web, hyphens are calmer.

The 260-character trap

Windows traditionally limits the whole path – drive, all folders and the file name together – to 260 characters. It is not the name alone that counts, it is the entire chain.

That sounds generous and is not: a path inside a synced cloud folder, three levels deep, with descriptive folder names, reaches 200 characters quickly. The rest is all your file name gets. The symptoms are copy errors nobody understands – “the path is too long” is the friendliest of them.

The remedies are unspectacular: flat folder structures and file names that describe rather than narrate. “2026-03-14 City Utilities annual statement.pdf” is good. “2026-03-14 Annual statement from City Utilities for the flat on Sample Street including the additional payment.pdf” is an essay.

Versions: v1, v2, final, final2

Everybody knows the chain “Quote_final.docx”, “Quote_final2.docx”, “Quote_final_really.docx”. It happens because “final” carries no information – it is a hope, not a state.

Put the date at the end instead. “Quote 2026-03-14.docx” and “Quote 2026-03-21.docx” tell you immediately which one is newer, and the chain can grow as long as it likes without becoming embarrassing.

Renaming hundreds of files at once

For the simplest case Explorer is enough: select all the files, press F2, type a name, press Enter. Windows then numbers them through – “Holiday (1).jpg”, “Holiday (2).jpg”. It is crude, but for a series of photos it is often exactly right.

If you need more – search and replace, numbering with leading zeros, a preview before renaming – it is in Microsoft’s PowerToys under the name “PowerRename”. Free, and from Microsoft themselves.

With Zortio

While filing, Zortio can append the date modified to the file name – “holiday.jpg” becomes “holiday_2026-03-14.jpg”, in the format above. That gives a usable date in the name even to files that never had one, hundreds at a time.

The preview shows you every new name beforehand. With a bulk rename that is the decisive point – and if something does not fit after all, “Undo” restores the old names too.