To know how fast someone is going, the key concept is speed, which is defined as the distance traveled divided by the time taken. Speed can be instantaneous (at a specific moment) or average (over a period). The usual units for speed include kilometers per hour (km/h), miles per hour (mph), and meters per second (m/s). To find out the actual speed:

• One can use a speedometer if in a vehicle.
• For a moving person or object, GPS-based online speedometers or apps can measure real-time speed.
• The formula for average speed is: average speed = total distance / total time.

Therefore, to answer "how fast am I going," one typically needs to measure either distance and time or check a device that shows instantaneous speed, such as a car speedometer or a GPS speed measurement tool.