When Is A Gigabyte Not A Gigabyte?

July 14, 2008 – 5:20 pm

We've all run into it.  You get your computer with the 300 gigabyte drive and when you look at the space free, it says that the drive's capacity is actually 279 gigabytes.  You think you were a victim of false advertising until you read the fine print.  The manufacturer measures a gigabyte as 1 billion bytes and you find out that your computer measures it as 1,073,741,824 bytes.

This is because your computer does things in powers of two, so it sees the border between byte, kilobyte, megabyte, etc, not as 1,000, as you'd have in decimal between thousand, million, billion, etc., but as 1024 which is 2¹⁰. So a kilobyte is 1024 bytes, and a megabyte is 1024 kilobytes, and a gigabyte would be 1024 megabytes. Each time you go up a level (we're up to terabyte drives now, but they're not super common yet), the disparity between the manufacturer's stated capacity and the capacity the computer presents to you is going to get bigger.

But what is this loss of storage capacity really equal to? If you had a one-gigabyte drive, measured at 1 billion bytes, then you're losing 73,741,824 bytes. If you're using an 8-bit encoding scheme like ASCII, then one byte is one letter. In a previous article on the value of 1,000 words, we agreed on a value of 6 characters being the average length of a word. So the difference between the manufacturer's gigabyte and your computer's gigabyte is 12,990 words, or just short of 52 typed, double-spaced pages.

Now, when we went by the numbers in the ton of money post and the correlation of that with a ton of words in the value of words post, we got 137.78 words per penny, meaning that every gigabyte of storage is robbing you of 94 cents worth of words.

But that number may be a little inaccurate. First, it's only the storage space needed to hold the words that you're losing, not the words themselves. You're losing space in the bucket, not the milk that would fill it, so we can't give that space the same value as the milk.

Second is that hard drive space costs about 20.31 cents per gigabyte. If you price hard drives at NewEgg.com, you'll find 320 gigabyte hard drives going for $64.99. At 94 cents worth of words per gigabyte, the missing storage space would be worth 300.80, or roughly 4.6 times the cost of the drive. How can the missing 73 million bytes per gigabyte be worth 94 cents when you're only paying 20.31 cents per billion bytes of space?

At 20.31 cents per gigabyte, on a 320 gigabyte drive, that missing 73,741,824 bytes per gigabyte is worth around $4.79.

Can you come up with some Rough Equivalents for that missing 73,741,824 bytes? Post them in the comments below.

One last note, I was feeling artistic this weekend. Check out my drawing of a suicidal giraffe.