Drawing Square Selections

So far, we've seen how easy it is to select a rectangular-shaped object or area in a photo with the Rectangular Marquee Tool, but what if you need to select something that's perfectly square? Is there a way to force the selection outline into a square? Not only is there a way to do it, there's actually two ways to do it, although one of them is much faster than the other.

Here's a photo I have open in Photoshop of some rather grungy looking tiles:

Let's say I want to select the tile in the center so I can use it as an interesting background or texture for an effect. Since the tile is obviously square, we'll want to constrain our selection to a square. First, we'll look at the long way to go about it.

Any time the Rectangular Marquee Tool is selected, the Options Bar at the top of the screen will display options specifically for this tool. One of the options is called Style, and by default, it's set to Normal, which means we're free to drag out any size selection we need with any dimensions. To force the selection into a square, first change the Style option to Fixed Ratio, then enter a value of 1 for both the Width and Height options (1 is the default value for the Width and Height so you may not need to change it):

This forces the selection into a width to height aspect ratio of 1:1, which means the width and height of our selection will always be equal to each other, which means we can now easily draw out a perfect square. I'll click with my mouse in the top left corner of the tile to begin my selection, just as I did previously, and with my mouse button still down, I'll drag towards the bottom right corner of the tile. This time, thanks to the options I set in the Options Bar, my selection outline is constrained to a square:

Once again, there's no need to start over if you didn't begin your selection in the right spot. Just hold down your spacebar, drag the selection to its new location, then release the spacebar and continue dragging out the rest of the selection.

To complete the selection, I'll release my mouse button, and we can see in the document window that the square tile in the center is now selected, ready for whatever I decide to do with it:

The only problem with using this method to force the selection into a square is that the options in the Options Bar are "sticky", meaning they don't automatically switch back to their default settings the next time you go to use the tool. I can't even begin to tell you how many times I've tried to drag out a rectangular selection only to have the selection constrained to a square or some other aspect ratio because I forgot to change the Style option back to Normal. So, before we go any further, let's change it back to Normal right now:

The Keyboard Shortcut
A much better way to constrain a selection to a square with the Rectangular Marquee Tool is with a simple keyboard shortcut. Click on the starting point and begin dragging out a rectangular selection as you normally would, then hold down your Shift key as you continue to drag. As soon as you press the Shift key, you'll see the selection outline jump to a perfect square. Keep holding the Shift key down until you're finished drawing the selection. Release your mouse button to complete the selection, then release the Shift key.

The order you do things here is important. If you release your Shift key before releasing your mouse button to complete the selection, your selection outline will jump back into a rectangular shape and you'll have to press and hold the Shift key again to switch back to the square. Also, if you hold the Shift key down before clicking to begin your selection, you'll enter the Add to Selection mode, which isn't something we need to get into here but it could give you unexpected results if you already have one selection active and try to start a new one. So remember, to constrain the selection to a square with the keyboard shortcut, first click to set a starting point and begin dragging, then hold down the Shift key. Release your mouse button to complete the selection, then release the Shift key.

Next, we'll learn how to drag a rectangular or square selection out from its center!

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