How big is my Macbook hard disk?

The easiest way to figure out how much space is left on your hard disk is in Mac OS X is actually to go to the Finder and click on the hard disk icon, then look at the bottom of the window:

You can see I'm running a bit low on space, but not terribly. Since there's no percentage of space available or anything, there's no way to extrapolate total available disk space.

So how do you do it?

Here's how.

Start by choosing Apple --> About This Mac:

Which leads to:

That's an easy way to check how much RAM you have installed and what exact version of Mac OS X you're running, but what about the hard disk? To find out, click on "More Info..." and it launches the System Profiler:

Here you can see that it shows the basic information about your computer. I'm running this test on a Macbook Air, version 1.

On the right side, look for "ATA" and click on it, and if you've a computer with an ATA drive, you'll see something like:

There's your answer.

If you don't have an ATA drive, however, you might see something more like this:

This means that there's an ATA interface in the computer, but no drive hooked up. Instead, it's actually hooked in to the Serial-ATA (SATA) device plug. In this case, look on the left side just a bit lower and you'll see Serial-ATA. Click on it:

That should make everything clear. If that doesn't work, the only other possibility, though not on a Macbook, is SCSI.