AT&T's shared data plans will launch on August 23, allowing subscribers to connect several phones, tablets, laptops, and hotspots under one big pool of data.

Unlike Verizon's similar "Share Everything" plans, AT&T's so-called "Mobile Share" plans won't be mandatory for new subscribers. Individual and family plans will still be available, and existing customers can hang onto their current plans as well.

Still, for some families or individual users, switching to shared data might be a good thing. Such a switch could lead to lower monthly bills, and more service for their money. Here are some tips for figuring out whether shared data is worth it for you:

Do the Math

AT&T's cheapest shared data plans are more expensive than basic individual and family plans, but they include unlimited voice calls and text messages. Shared data is probably a bad deal if your existing plan only has the bare minimum for talk and text. If you've already using unlimited talk and text, switching to shared data may lower your bill and allow you to connect more devices for less money.

Things get tricky when you're somewhere in between on voice and text, or when you're dealing with several phones, tablets and hotspots. Get out a calculator and check the billing chart for AT&T's shared data plans, and compare it to what you're paying now.

Calculate Your Data...

The nice thing about shared data plans is that you can save money by getting a smaller shared amount of data. For instance, a family of four could share 6 GB of data instead of paying for four separate 3 GB plans.

To figure out how much data you're using, login to AT&T's Website, then navigate to Billing Reports. Under the drop-down list that reads "Report," select "Web Usage Volume by Wireless Number" and click "Submit." You'll be able to see how much data each device has used over the last several months. You can also call *3282# from your AT&T handset to see how much data you've used so far this month.

...But Beware of Overages

AT&T's shared data plans come with one big gotcha: Overage charges for data are $15 per GB, instead of $10 per GB on individual and family plans. Because the penalties for exceeding your limit are more severe, you'll need to be careful about getting a plan that cuts it too close.

Don't Forget About Hotspots

With shared data plans, AT&T doesn't charge extra to use a smartphone as a wireless hotspot. So why pay $10 per month extra to connect a tablet, or $20 per month to connect a standalone hotspot or laptop? Use your phone's hotspot functionality instead. It's cheaper and more versatile--and a lifesaver if your home Internet connection ever goes down.