Every once in a while, I like to do a post responding to frequently asked reader questions. One is how certain paper sizes compare to one another. I’d eventually love to do a post discussing the histories of the various paper sizing systems, from the rather simplistic U.S. letter/legal system to the much more complex international sizing standards, but today I plan to start by clearing up what companies mean when they say that paper is “A4” as opposed to “B6 Slim”. Where I have examples available in my personal stash, I post comparison photos below.
U.S. Paper Sizing
Most of us here in the U.S. grew up on two paper sizes: Letter and Legal. As far as smaller notebooks and notepads go, you’ll find all sorts of non-standard variations, though for pocket notebooks most companies appear to have settled on the “Field Notes” 3.5” x 5.5” as a standard.
U.S. “Letter Size”: 8.5” x 11”, or 216mm x 279mm
U.S. “Legal Size”: 8.5” x 14”, or 216mm x 356mm
Pocket Notebook: 3.5” x 5.5”, or 89mm x 140mm
Stacked Writing Pads: A4 (bottom) vs. Letter (middle) vs. A5 (top). Letter size is both wider and shorter than A4.
International Paper Sizing
In most countries outside of the U.S., paper tends to be sized according to the “ISO Standards” system, which is much more detailed and provides many more options for specific categorization. A good breakdown of the system (and many other regional and/or traditional sizes) can be found here. This post is not intended to be exhaustive, though I think it hits the most frequently encountered paper sizes available on the current market.
A4: 8.3” x 11.7”, or 210mm x 297mm (standard “international letterhead” size)
A5: 5.8” x 8.3”, or 148mm x 210mm (standard “international notepad” or “Moleskine-style notebook” size)
A6: 4.1” x 5.8”, or 105mm x 148mm (standard Hobonichi Techo size)
B5: 6.9” x 9.8”, or 176mm x 250mm
B6: 4.9” x 6.9”, or 125mm x 176mm (less popular than B6 slim, at least in the U.S., but I carry at least one example in the shop from Kleid x Life)
B6 Slim: 4.2” x 6.9”, or 106mm x 174mm (more popular than standard B6, with both Midori and Nanami Paper using this for their cafe-style notebooks)
“Traveler’s Standard”: 4.3” x 8.3”, or 110mm x 210mm (I’ve seen this size referred to as everything from “A5 Slim” to “Travel” to “Personal.)
“Traveler’s Passport”: 3.5” x 4.8”, or 89mm x 124mm (shorter and wider than a Field Notes notebook)
A5 Stálogy Notebook vs. Traveler Size Standard vs. B6 Slim
Disclaimer: This guide is intended for general comparison purposes and quick reference only. There may be variations in size across brands and regions. For example, one company’s “A5” may be slightly larger or smaller than another company’s, even though they should be standard. Don’t rely on this or any other size guide alone if you are looking to purchase a cover or folio “that will fit _____ notebook or refill.” The only way to be sure is to test it out in person or to buy a notebook cover specifically advertised as intended for that brand.