If your work runs on week numbers, you want the current one where you can see it: in the menu bar, and down the side of the month grid. macOS does not show it. This guide explains why two people can disagree about what week it is, which Mac apps show week numbers, and how to put one in your menu bar.
Why week numbers differ: ISO 8601 and the US convention
ISO 8601, used across Europe and in most business software, starts the week on Monday and makes week 1 the week that holds the first Thursday of January (equivalently, 4 January). A year has 52 or 53 ISO weeks, and 29, 30 and 31 December can belong to week 1 of the next year, or 1, 2 and 3 January to week 52 or 53 of the previous one.
The US rule, which macOS uses for an en_US region, starts the week on Sunday and makes week 1 the week that contains 1 January, however short. So 27 December 2026 is already week 1 of 2027 by the US rule, while ISO calls the same Monday-to-Sunday span week 53 of 2026.
Which one you want depends on your team, not your taste. If a supplier says “delivery in week 2” and you are in a Sunday-first locale, ask which rule they mean.
Ways to show week numbers in the Mac menu bar
Checked on 6 November 2026.
| Option | Price | Runs on | How |
|---|---|---|---|
| macOS itself | Built in | Any | No week number in the menu bar. Calendar.app can show them in its month view (settings, Advanced). |
| Week Number (Sindre Sorhus) | Free, App Store | macOS 26 | Just the week number in the menu bar. |
| Itsycal | Free | macOS 27 (0.28.0), or 11 to 26 (0.15.15, frozen) | W toggles the grid column (ISO only, Monday start); w in the clock pattern puts it in the menu bar. |
| Dot | $14.99 once | macOS 13 and later | A Week token for the menu bar and week numbers in the grid. |
| Calendr | Free, open source | macOS 15 and later | A menu bar calendar with a clock pattern and a week-number column in the grid. |
| Blipcal | $19 once | macOS 14 and later | ISO or your region’s rule in the grid (W toggles it), and w or ww in the menu bar pattern. |
Prices and minimum macOS versions as published on 6 November 2026; confirm before relying on them.
Show the week number in Blipcal
Press W
With the panel open, W shows a week-number column down the left of the grid. Or turn on Show week numbers in Settings > Appearance.
ISO or your region
If the week starts on Monday, the numbers are ISO 8601. Any other first weekday uses your region’s rule. Set the first weekday in the same tab.
Put w in the menu bar
Settings > Menu bar: add w to the pattern, for example E d MMM ’W’w. Quoted text stays as typed.
Check the preview
The preview under the field shows exactly what the menu bar will say, and updates as you type.
Itsycal’s week numbers
If you are on Itsycal, you already have most of this: W toggles the week column, and w in the clock pattern puts the number in the menu bar. The column is ISO only, with Monday as the first day. The frozen 0.15.15 build for macOS 11 to 26 does this too; it is one of the features that predates the split.
Want week numbers in the grid and the menu bar, either convention? Read about Blipcal: a 14-day free trial, every feature, no card.