How to Change the Date and Time Format on Mac

Date and time formats on a Mac come from two places: Language & Region decides how every app writes dates, and the Clock options decide what the menu bar shows. Change the right one and 12/31 becomes 31/12 everywhere — or just in the corner of your screen.

Region sets the baseline

1. Open System Settings → General → Language & Region.
2. Check the Region setting. It drives the default date order (day-first vs month-first), the first day of the week, number separators, and measurement units in one go.

You don't have to "live" in the region you pick — choosing United Kingdom is the classic way to get day-first dates and Monday weeks with English text. Apps pick the change up immediately; a login cycle clears out any stragglers.

Fine-tune in the same pane

• 24-hour time — its own toggle, independent of region. This affects clocks and times system-wide, including the menu bar.
• Date format — on macOS Sonoma and Sequoia, Language & Region includes a date format picker with concrete samples (like 8/26/24, 26/8/24, 24-08-26), letting you override just the date order without changing region. On Ventura this picker doesn't exist — the region choice decides, so pick the region whose format you want.
• First day of week and calendar — separate settings here too, useful when your region default doesn't match how you plan your week.
• Temperature and measurement — same pane, same logic, worth fixing while you're in there.

Everything here is freely reversible — set Region and the toggles back and the old formats return.

The menu bar clock has its own switches

What the top-right corner shows is styled separately:

1. Open System Settings → Control Center and scroll to the Clock section (the Clock Options button).
2. Set Show date to Always, When Space Allows, or Never, and toggle Show the day of the week.
3. Pick Digital or Analog, and for digital: Use a 24-hour clock, Display the time with seconds, and Flash the time separators if you want the colons to blink.

Note the menu bar's 24-hour switch is separate from the system-wide one in Language & Region — you can run a 24-hour menu bar clock on an otherwise 12-hour Mac, or vice versa.

Where the formats show up (and where they don't)

Language & Region formats flow into Finder's date columns, Mail timestamps, Calendar, screenshots' default names, and any app that asks the system how to write a date. What they don't override: apps with their own format settings (spreadsheets are the big one — Excel and Numbers format cells per-document) and web apps, which follow the website, not your Mac.

Region and language are separate dials

A common hesitation: "if I switch Region to the UK, will my Mac start spelling colour with a u?" No — Region controls formats (dates, numbers, currency, week start) while the language list above it controls the interface language, and they move independently. A Mac in US English with an India region setting is a perfectly normal combination: day-first dates, ₹ as the currency symbol in apps that ask, Monday weeks if you set it, English interface untouched. That separation is also the escape hatch when a format annoys you — you never have to change language, and if a region switch has side effects you dislike (temperature units, say), the individual overrides in the same pane put each one back.

Want the clock to show seconds?

For timing anything — screen recordings, cron jobs, rendering — a seconds readout in the corner is quietly useful. Here's how to show seconds in the menu bar clock, and what it costs you in space.