How big is a gig (or a GB), anyway?

Whenever the subject turns to smartphones, wireless data plans, or PCs in general, we inevitably start talking about gigabytes—as in, “Did you get the 16 GB iPhone, or the 32 GB model?” Or, “Argh, my new Verizon data plan has a 5 GB limit!” Or maybe, “Check out my new 16 GB USB drive—it’s no bigger than a dime!”

OK, but here’s the question: What is a gigabyte (or a GB), and just how big are they, anyway?

Not quite sure? Relax; I promise you’re not the only one.

So, let’s tackle the nitty-gritty first. A gigabyte is a unit of digital storage—a relatively big one, in fact. (Some real-world examples are coming up.)

Now, the very smallest unit of data is the “bit”—a simple “0″ or “1,” open or shut, yes or no. If you were to ask me, for example, “Is your name Ted?”, then my answer—”no”—would give you (literally) a single bit of information about my name.

Alright, got your calculator ready? Take eight of those zero-or-one, yes-or-no “bits,” put ‘em together, and you get a single byte—a unit of data that’s considerably more complex than a bit, yet still a mere speck in the grand scheme of digital storage.

Now, put about 1,000 (or 1,024, to be precise) bytes together, and you get a kilobyte, commonly abbreviated as KB. How big is a kilobyte? Well, consider this: is takes about 20 KB of memory to store a single, text-only email message.

Next, take 1,024 kilobytes, toss ‘em in a bucket, and you end up with a megabyte (MB)—and now we’re finally getting somewhere. With a single megabyte of memory, you can store about three average-size webpages—or one quarter of a your average, ten-megapixel digital photo. A typical song from iTunes, meanwhile, weighs in at about five MB.

Last but not least, grab a bundle of 1,024 megabytes and you’ve got yourself a gigabyte (GB), a fairly hefty load of data (for now, anyway).

What fits in a single GB, you ask? Try this on for size:

• A 90-minute, standard-definition movie on iTunes
• A pair of 45-minute TV episodes (again, in standard-def, not HD)
• About 200 songs
• About 250 pictures (from a 10-megapixel camera)
• Or about 500 e-books (assuming they’re an average of 2 MB each)

That means the 16 GB iPhone will store more than 3,000 songs, or 8,000 Kindle volumes, or a season and a half of “The Good Wife.” (Keep in mind, of course, that episodes of “The Good Wife” won’t be the only thing saved in your iPhone’s memory.)

Sounds good—but what does a GB mean when it comes to choosing a smartphone data plan? After all, AT&T only lets its subscribers consumer two GB of data a month for its $25 “DataPro” plan, while Verizon recently capped its $30 smartphone data plan to two GB a month.

Well, a GB of smartphone data is good for…

• About 8 hours of YouTube video (if your eyes can take it, that is)
• Three-plus feature-length “instant” movies on Netflix
• More than 50,000 text-only email messages (both sent and received)
• Almost 3,500 emails with Microsoft Word attachments
• Or about 5,800 average-size web pages

Again, remember that you won’t only be, say, streaming video or sending email on your smartphone, so bear that in mind as you do the calculus on how much smartphone data you’ll need each month.

Have more questions about all things KB, MB, or GB? Let me know!

(Note: Many thanks to the Clicker blog and AT&T’s Data Calculator for their facts and figures on smartphone data use.)

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