To measure how fast you are moving, whatmylocation.com requires your device's location permission. Based upon your device location, the location details returned for the queries like "how fast am I moving and show my device's current speed" deemed to be how fast are you moving and show your device's current speed.
How fast am I moving? - shows how speed are you walking, running, moving or traveling right now in miles and kilometers. Calculating your velocity is useful to estimate the time to reach your destination. Divide the total (remaining) distance by speed, you will get the time to reach your destination of your interest. Click on
What My Location to know more about your current location right now, including the details of surrounding or nearby places.