Get Info
Mac Tip#53/01-May-2002

Tip 52 explained units of measurement such as Megabytes and Kilobytes. This Tip looks at how to find out how big a file or folder is on your computer.

In fact there are several ways. For one, you can just view your window of files as a list (see Tips 14 to 17). One of the columns should show file size. Unless you switch it on though, this doesn’t show the size of your folders.

Comparing 2 Get Info windows.

Another way is to “Get Info”. Just find the file or folder whose size you want to know and click once to select it. Now go to the File menu and choose Get Info.

Depending on what you’re “Getting Info” on you’ll see various items of information. There are basically 3 kinds of files you could Get Info on: folders, documents and applications. Each kind of file will show a size, but applications will generally show a version number, folders will show how many items they contain and documents will show which application “owns” the file.

The size can sometimes be a little confusing too. If you look at the screenshot on this page you’ll see I’ve got Info on two files: one is called v and the other’s called vvv. V contains only one letter v, while vvv contains 3276 characters. They shouldn’t both be the same size, yet both are 8K.

If you look more closely, you’ll see that in fact they aren’t the same size: one is 973 bytes, while the other is 4248 bytes. 8K should be 8192 bytes, more than either file has.

The one with 973 bytes is the one which contains a single letter, while the larger one contains thousands of letters. 973 bytes is the actual size of the smaller file, but because your Mac needs to set aside space beforehand for all the files it simply divides the available space into equal size blocks. In my case each block is 8K in size. Each file is placed in its own block (or series of blocks if it needs more than one), so even the smallest file still uses up a whole block.

It’s a bit like a chest of drawers: I might have one pair of socks in my sock drawer or I might have so many pairs of socks I need several drawers, but the chest of drawers still has a fixed size for each drawer. The drawers don’t change in size.

OS 9 vs OS X

The Get Info window behaves a little differently depending on whether you use the traditional Mac OS (9 and earlier) or OS X.

In OS X there is only one Get Info window. If you have the Get Info window open and you select another file the Get Info window changes to show information on the new file. Under OS 9 and earlier you can have a whole pile of Get Info windows open — one per file.

There’s also more you can do with the Get Info window, but that’s a subject for more Tips.