You're writing dates wrong

Let me start with a confession: for years, I wrote dates like most people do. DD/MM/YYYY. It made sense. In the UK, we read left to right, and day first feels natural. Americans write MM/DD/YYYY. I still don’t know why. However, I stopped caring because both ways are wrong.

The format everyone should use

ISO 8601: YYYY-MM-DD.

2026-05-11

That’s it. Year first, then month, then day. Separated by hyphens. Four digits for the year, two for everything else. No ambiguity. No surprises.

Why does this matter? Because dates are everywhere, especially in content management, and the format you choose has consequences that cascade through everything.

It sorts itself

This is the single best reason. When you store dates as YYYY-MM-DD, they sort lexicographically (alphabetically) in the right chronological order.

2020-01-15    ← first
2021-03-22
2022-07-04
2023-12-31    ← last

Try that with 15/01/2020 or 01/15/2020. The files arrange themselves correctly in a folder, in a file list, in a database, in a spreadsheet, in a git log. Everywhere. Without you asking it to.

That might sound like a tiny thing. Until you’ve spent an afternoon manually rearranging a year’s worth of blog posts or annual reports.

There’s no ambiguity

• 03/04/2023 — March 4th or April 3rd?
• 25/6/23 — Is that a two-digit year? A day? Could it be last century?

With ISO 8601, there is exactly one reading. Always. No context needed. No guessing. No asking the person who wrote it.

You don’t need to remember which format is UK, US, or “the one Dave uses”.

It works everywhere

ISO 8601 isn’t a suggestion. It’s a real international standard. And because of that, every tool that handles dates knows it:

• Spreadsheets recognise it without configuration
• Databases parse it natively
• Git commits get chronological ordering for free
• Static site generators (like Hugo) expect it for front matter
• Email clients interpret it correctly in message headers
• Search engines understand it for date-based filtering
• Backup systems sort archives correctly
• Your future self can read it without squinting

Try the same in 12/03/23 with a spreadsheet that’s set to a different locale and you’re suddenly guessing again.

It future-proofs your content

This ties back to the same principle I wrote about in Allow your content to outlive your website : keep it simple, keep it standard, keep it portable.

The more idiosyncratic the formats you use, the more fragile your content becomes. When you standardise on one clear, universal format, your content isn’t tied to any one tool, platform, or region.

That’s what “future-proof” really means. Not fancy technology. Just not making things unnecessarily complicated.

The takeaway

YYYY-MM-DD is not complicated. It’s not fussy. It’s not some nerd thing.

It’s the format that just works. Everywhere, all the time. Without you thinking about it.

And honestly? That’s about as good as it gets in the world of standards.