Most digital planners are sold in two sizes, and the choice matters less than the listing makes it look. Here’s the short version: pick the one shaped like your screen.
They’re not sizes, they’re shapes
Nothing here gets printed, so the inches are beside the point. A digital planner opens at whatever size your tablet is, and both versions fill it. What actually differs is the proportion of the page.
A4 is 210 by 297 mm, which is the taller, narrower page. Letter is 8.5 by 11 inches, slightly wider and noticeably shorter. Put them on top of each other and A4 is the long one.
That difference is small on paper and visible on a screen, because a screen has a fixed shape and any page that isn’t that shape gets empty bands down the sides or across the top.
So match it to your tablet
Tablet screens come in two rough shapes, and the two paper sizes line up with them almost exactly.
An 11-inch iPad Pro, an 11-inch iPad Air, or a standard iPad has a wider screen, and A4 is the closer fit. Turned landscape, an A4 page very nearly fills it.
A 12.9-inch or 13-inch iPad has a squarer screen, closer to old 4:3, and Letter sits in it better. A4 on a 13-inch leaves a band above and below.
An Android tablet is usually wider still, so A4 is the safer pick.
If you’re between the two, or on an older 4:3 iPad, either works and you will not spend the year thinking about it.
The part everyone gets backwards
Your country doesn’t come into it.
A4 is the standard paper size across most of the world and Letter is the North American one, and that’s a real difference — for printing. For a file you only ever open on a tablet, the fact that A4 is what your printer holds tells you nothing about what looks right on your iPad. Plenty of people in the US are better off with A4 and plenty of people in Europe are better off with Letter.
The exception is if you’re actually going to print — note templates, occasionally, or a printable. Then buy the one your printer takes, and buy it for that reason.
What doesn’t change
Neither size gives you more room to write. Both scale to the screen you’re on, so a weekly spread on Letter and the same spread on A4 hold the same amount of week.
The page count can shift a little between the two, because a taller page fits another row or two, and a planner’s undated sections sometimes come out a few pages apart between shapes. It’s a rounding difference and not worth choosing on.
If you pick the wrong one
Nothing breaks. The planner opens, the links work, the writing works. You get a border of dead space that you’ll notice for a week and then stop seeing.
Worth knowing because these are usually sold as separate files, so switching means buying again. Spending thirty seconds on it now is cheaper than being annoyed later, and being annoyed later is the worst case, which is a fairly mild worst case.
Where to go next
- Portrait or landscape? — the other half of this decision, and the one that actually changes how you plan
- Choosing a digital planner — everything else worth checking
- Digital Note Templates — note templates come in both sizes too, and the same rule applies