Microsoft 365 (Word) Paper Sizes

I ran into the same confusion before, so I totally get where you’re coming from. The issue here isn’t the paper or Microsoft 365—it’s the on-screen ruler. Online/onscreen rulers almost never match physical measurements unless your monitor’s size and display scaling are perfectly calibrated, which is really rare.

For Microsoft 365 (both the web and desktop versions), when you choose Letter 8.5" x 11", it really does mean U.S. Letter size:

Width: 8.5 inches (216 mm)

Height: 11 inches (279 mm)

That’s the physical, real-world size of the paper you buy at the store. Microsoft uses those exact dimensions for page layout, margins, and printing.

So if your printer paper says 8.5" x 11", it actually is that size—you just won’t see it correctly when measuring against an onscreen ruler because the monitor scaling throws things off. If you put a real ruler against the paper itself, it should measure exactly 8.5 by 11 inches.

In short: the software dimensions are correct, but onscreen rulers can’t be trusted for physical measurements unless everything is precisely calibrated.