This is a review of Sensorly, one of the best iOS apps for measuring cellular carriers’ signal strength on your iPhone or iPad (Mini).

We’ve all been there. You grab your iPhone or iPad Cellular (Mini) to find the best restaurants nearby, the weather forecast, or information about an upcoming event and you realize that you’re outside your carrier’s data coverage area. If this happens frequently, you might be interested in discovering which carriers have better data coverage in your area. Or, you might just wish you could find your way to a nearby area where your carrier offers better coverage.  If you find yourself in either of these situations, an app called Sensorly can help you out.

Sensorly does two primary things. First, it collects signal strength information from real-world cellular devices on pretty much every major cellular carrier and then displays it on color-coded Coverage Maps. The second feature that Sensorly offers is to test how fast your carrier is at your current location by performing a data Speed Test.

Coverage Maps – Sensorly’s primary feature is to display data signal strength for a wide range of cellular carriers on an interactive, color-coded coverage map.

Once you select a carrier (e.g. Sprint, Verizon, AT&T) and a band (e.g. 3G, WIMAX, LTE), Sensorly displays your current location on a map. Signal strength is represented by color-coded blobs. The darker the blob, the stronger the signal strength.  This color-coded system makes it easy to compare signal strength between carriers in a given area or to find a location close by where your current carrier offers stronger signal strength.

Tapping on the gears icon accesses a helpful “Settings” page with a map legend, different map views, and other options.

As you can see, Sensorly offers information on an extensive list of cellular carriers. I would venture to say that nearly every major cellular carrier is represented, not just in the United States but globally. This makes it a very useful tool for comparing data coverage if you’re shopping for a new carrier in your area or if your’e moving somewhere new and would like to see which carriers offer the best coverage there.

Speed Test – Sensorly’s Speed Test feature is extremely useful for determining actual download and upload speeds on your carrier’s network at your current location. Essentially, Sensorly downloads and uploads test data packets to measure your network’s actual speed.  A disclaimer for this feature: If your plan does not include unlimited data, you might want to use it sparingly. The speed tests I used expended around 25 MB of data. If you have an unlimited data plan, though, then this won’t be an issue; feel free to test away.

Sensorly’s Coverage Maps and Speed Test can be used together to give you a very clear picture of your cellular carrier’s coverage. I’ve been using it to monitor my carrier’s (Sprint) progress as they turn on their LTE network in my home city. The app is definitely useful for determining signal strength at my current location and across town. It’s also interesting to occasionally view other cellular carriers to compare their coverage with Sprint’s.

Currently, Sensorly is available for free on iOS’ App Store. Give it a try and use it to gain a better picture of cellular coverage in your area. Tap here to go to the App Store and download the app now: Sensorly