You are looking hot today. Literally: With a thermal camera, I can see that you have a body temperature of over 102 degrees Fahrenheit, so you’ve got a fever. Not only that, but I can see where your hot water pipes are in the wall, determine if your electrical cables are overheating, and locate your dog outside on a moonless night.
All these things, and many more, are possible with thermal cameras that clip onto your phone and display images captured with an infrared light sensor that shows how much heat objects are giving off. Infrared light is normally invisible, but these cameras render it visible through your phone’s screen, allowing you to study the differences in temperature between hot or cold things and their ambient surroundings. These cameras can also help you see how well your home insulation works, showing hot spots where heat is escaping and wasting your money.
All the cameras I tested use a smartphone to do the heavy lifting of processing, showing, and sharing images through apps that are available for free. I tested the USB-C versions for Android phones of the Flir, Seek Thermal, and Uni-T cameras, and the iPhone version of the Perfect Prime camera. All the manufacturers make versions of their cameras for both Android and iPhone. Also, Flir recently released a new mobile camera, the $550 Flir One Edge Pro. I haven’t tested it, but this guide will get an update once I have.
Check out our other buying guides, including the Best Android Phones, Best Cheap Phones, Best iPhones, and Best Camera Gear for Your Phone.