There's no shortage of options for creating collages on a Mac. A search for "collage" in the Mac App Store brings up a bunch of options.
TurboCollage is by no means the only option available. And it's not the cheapest, although at under $10 it's very reasonably priced. But I've found it to be one of the most flexible and no-nonsense options in creating collages. Not surprisingly, it's also one of the highest rated.
Importing Your Photos
When you first open TurboCollage for Mac you get a blank canvas and not much in the way of guidance about where to start. While you don't have to do it this way, it makes sense work from left to right, starting with the Pictures tab at top left.
Make sure that Pictures tab is highlighted, and then use the small Plus button to open a Finder browser to select your images. You can also just drag image files from Finder into the left panel.
I'm going to use a set of photos from the beautiful beaches of St John in the US Virgin Islands for this example.
When I first image them they're just thrown randomly on the workspace and all sized pretty uniformly.
Choose a Pattern
After you've imported your photos, it's a good idea to move to the next tab, Settings. That's where you set the basics of your layout and the size of your output file.
When you first import photos, the default pattern is a Picture Pile. That's designed to look like a bunch of photo prints thrown on a table. One of its key characteristics is that it's also 3-dimensional, so some photos lie on top of others.
With the Picture Pile pattern, if you click on any photo you can drag it wherever you like. When you click on an image you'll also see a small rotate button appear. If you click and hold on that you can rotate and resize. If you click and hold, you can also rotate and resize (just click near the edges of a photo
You'll notice that with each of these Patterns, the available buttons directly below the images changes. With the 2-dimensional patterns, there's obviuosly no need to be moving images forward or back.
If you're using the Picture Grid pattern, you can also control how many rows and columns to use (this option isn't available with the other patterns).
The Mosaic pattern automatically arranges the images to fill the entire space. It means that the cells are not a uniform size.
The Center Frame pattern makes the center image larger and reduces the size of the others.
It's distinctive, but it's not really one I find myself using much.
Set Your Layout
In the next section down in the left panel you have Layout options. These set the size of your output file. With the drop-down menu you can set your aspect ratio to fit your desired output. It comes with a bunch of default options for common sizes and outputs.
One of the handiest options is the ability to create a Custom Size.
In this example, I'm creating a Custom Size for a Facebook Cover Photo.
That changes the aspect ratio of the workspace so that what you see is what you get.
Now that the layout and pattern are in place, you can start changing the style. By dragging the sliders you can choose to have a lot of spacing between the images, some, or nothing at all. Some with whether or not to have rounded or square corners or something in between.
You can also set the color of the background from the default white, select a background image that sits behind all the others, or use an entirely transparent background (the latter only works if exporting to PNG, not JPG, since the JPG image format doesn't support transparency).
You can also control the shadows that each image throws onto the background by using the sliders or even turn them off by unselected the Draw Shadows checkbox.
This is what it looks like with both spacing and corners set to maximum.
And with them both set to minimum (ie. off).
One of the nice things about the program is that it makes rearranging the photos a snap. If you click on one and drag it, it will simply do a straight swap. That keeps everything nice and neat.
And you can also reposition and zoom. When you click on an image you'll get two small icons. The one on the left is for repositioning images (just click and drag). The one on the right is for zooming an image (again, just click and drag).
One thing you can't do is resize individual spaces.
If you like, you can also add text. But I find the controls here a bit too basic for my tastes. But you have basic text input and can choose the font style, alignment, text color, opacity, and shadows. Oddly, you can't change the font size, though. There are also limits to how much the available tools can make the text stand out from the images--I'd much rather do the text part in something like Photoshop, where there's a lot more control. But it's there if you want something basic.
Once you're happy with how it looks, just got o File > Export. You can export as a JPG, PNG, or TIFF file.
There are also buttons at top right to send by email (it opens the Mac Mail app--not necessarily your default email client) and to Facebook (requires logging in to Facebook, of course).
There are definitely some areas TurboCollage can be improved. When using the import photos browser, you can't use CMD+A (to do multiple, click on the first and then hold shift as you click on the last). There's no Undo option at all available anywhere in the program, which can catch you out if, like me, you're in the habit of relying on undo. You can't resize individual cells in the Mosaic pattern. The text options are limited to the point where I don't find them especially useful. There's no control over the quality settings when exporting to JPG. And it doesn't come with a lot of the pretty frames and patterns by default that some of the other apps come with.
But if you don't need all those frilly bells and whistles and just want something that gives you good control for creating photo collages, I've found TurboCollage to be one of the best apps available for the purpose, and it has become my go-to option for all but my most complicated collage needs.
Here's an example of a Facebook Cover Photo I created for my Facebook page with TurboCollage.
And here's another example of a different style that I created for the graphics for a post on this site.
Where You Can Get It
There are also versions of TurboCollage for iPad, iPhone, Windows, and Android.