Fitness trackers such as Apple Watch, Fitbit, Garmin and many more are great tools for motivating yourself and identifying tangible goals. However, as a note, everything the body does uses energy, including breathing or blinking the eyes. But the problem is that they cannot be counted without equipment connected to our body. Therefore, those basic calculators only ask for physical activities such as walking, running, cycling, swimming, dancing, active work, playing outside, etc.
However, this is not the case with the smartwatch, since it can detect the heart rate. Smartwatches use their built-in accelerometer to measure your movements. They'll also use your heart rate monitor to see how fast your heart is beating. The concept is that the faster your heart rate, the more calories you burn.