In the grand scheme of worries, deciding which size tablet to get -- they all sit within a roughly three-inch screen range -- does not quite rank.
But technophiles and technophobes alike struggle with the question. About half of the major tablets are the thickness of a failing magazine with screens about seven inches (measured along the diagonal), and the other half are about twice as thick with screens about 10 inches long.
Even if this isn't a life-changing decision, it can be a baffling one.
The companies that make tablets give some basic but vague guidance. Google's marketing materials say its larger 10-inch tablet is suitable as a "couch or coffee table companion" and its seven-inch Nexus 7 "is designed to go wherever you go." Peter Larsen, Amazon's vice president for the Kindle reader, says the seven-inch Kindle Fire HD is small enough to fit in a purse. He doesn't say where the 8.9-inch Kindle Fire HD fits.
Here's the first thing to keep in mind. It kind of doesn't matter. All tablets can browse the Web, check e-mail and run apps. Some are better at some things than others, but the difference in screen size does not fundamentally change the nature of the machine.
Sarah Rotman Epps, a senior analyst at Forrester Research, had a beautiful way of describing it to me. She said tablets of different sizes were like knives in your kitchen: "You can have a six-inch chef's knife or an eight-inch chef's knife or a paring knife, but they all cut food."
Ms. Epps said that people more often than not use tablets in their homes, where you'd think that more screen real estate would trump more portability. And Jakob Nielsen, principal of the Nielsen Norman Group, who has been studying user interfaces for almost 30 years, agreed. "When it comes to screen size, bigger is better," he said.
But I'm not sure that's the whole picture. All those benefits don't account for the popularity of smaller tablets.
I believe smaller tablets make up for their smaller screens and limited computing power by being easier to hold. That's different from portability.
Phones are light enough for anyone to hold, and laptops are never expected to be held for long, unless they're being toted in a bag. But tablets beg not only to be carried like magazines but to be held like them, too. This generation of midsize tablets is not only better out of the house, but more comfortable to hold in the home, on couches and in bed, where they are most often used. The bigger tablets weigh just enough to be annoying after a while.
So, I think you should get a little tablet in most cases. Except these:
YOU HAVE BAD EYES With less screen, text in a comparable app, magazine or e-book will never appear as large as on a full-size tablet.
YOU READ A LOT OF MAGAZINES Condé Nast magazines like GQ and Traveler have been redesigned on iPads to have scrolling pages with bigger text. But some smaller publishers simply port their magazines to tablets by producing what is basically a facsimile of a print page. When shrunk, these pages are nearly impossible to read on smaller tablets, whether they have high-definition screens or not, without zooming in.
YOU HAVE FAT FINGERS Mr. Nielsen says in a blog post about the iPad Mini that apps designed to run on the full-size iPad can't just be scaled down without making it harder to push on-screen buttons. Nielsen says screen resolution is not as important as buttons, which should be more than a square centimeter in size. I haven't noticed interface problems on smaller tablets, though.
YOU GIVE PRESENTATIONS Or you call yourself a photographer. Small tablets are clearly personal devices, but full-size tablets can double as sleek presentation tools for doctors displaying X-rays, architects showing off blueprints or sales people making pitches to prospective clients. They can get a lot out of the bigger high-definition screens on bigger tablets.
YOU WRITE A LOT OF MEMOS Or you write a lot of e-mails on your tablet. I don't get why you would want to do this on a small tablet. Joe Brown, editor in chief of the gadget blog Gizmodo, told me that even on big tablets, touch-screen typing is not as effective as using a physical keyboard. "You should also probably just stick with your laptop," he said. Unless you don't have one.
YOU WANT A POST-PC EXISTENCE People who are technophobic seem to take to tablets. You can learn to use them in seconds, there is no long boot-up delay and they rarely crash. Because the lightest laptops tend to be only a little bigger than tablets in screen size and only a pound or two heavier than a full-size tablet, you might as well get the bigger tablet.
YOU LOVE VIDEO GAMES If you're intent on buying a tablet with the ultimate in graphics performance, you should get a big tablet. Or an Xbox.
YOU ARE VERY BIG AND STRONG If you are an N.B.A. player, Olympian or a person of similar height, strength and weight, I'd guess a big tablet probably feels like a little tablet does to me. (I am a small Chinese-American man.)
Nathan Weiner, chief executive of Pocket, a service that lets people save Web clippings and view them later on any device, said of smaller tablets: "They're like books and they're a lot lighter, which is, to be honest, the biggest thing. The big iPad was always a lot of work. You're always trying to prop it up in bed or on a couch, and it always felt top-heavy. I don't want to make it sound like I have no arm strength, but it was less tiring in that regard."
In the end, my advice is that no matter what brand of tablet you buy, you should go to a local store that carries it (Apple or Best Buy should work fine) and try it out. Really try it out -- by testing apps, browsing the Web and looking at e-mail, movies and magazines, side by side. And for the sake of this conversation, hold it up the way you would at home for a few minutes. Get down on the floor, if you want. Irritate other shoppers by watching a few long YouTube clips or something. (You are about to part with several hundred dollars. You deserve to take your time with this.)
And if you are still afraid of choosing the wrong one, remember there is no wrong one. You cannot mess this up.
This article originally appeared in The New York Times.