Digital Bathroom Scales
Digital scales use load cells to convert the physical weight on the scale to an electrical signal that's displayed on a readout in increments as small as a tenth of a pound. In addition to greater accuracy, the advantage of having weight represented by an electrical signal is that it allows for a lot of added functionality. Some of that is fun stuff -- like the ability for the scale to speak your weight aloud, though those who are overly self-conscious about their weight might not find that a particularly helpful attribute. Other features are more useful, however. Some digital scales will also display your Body Mass Index (BMI), a measure of fitness that's based on your weight and height.Smart Bathroom Scales
Smart scales are digital scales that take things a step -- and in most cases, many steps -- further. They wirelessly connect to a smartphone, tablet or directly to the Internet via Wi-Fi and/or Bluetooth, and integrate with compatible apps and web sites to help you keep tabs on your overall fitness. Data transmitted includes weight, of course, but often other measures such as body fat, BMI, and more, such as heart rate. Many smart scales include built-in memory to store multiple user profiles and allow a single scale to serve the needs of an entire family. Some can display information collected from the web, such as the predicted weather.Body Fat Scales
These scales use a technique known as bioelectrical impedance analysis (BIA). Since fat and muscle have different resistances to electrical current, they attempt to gauge body weight/density by sending small electrical pulses through a user's body and measuring the time it takes to travel up one leg and down the other.