Warm up your body by walking at a moderate pace for the first five minutes of your workout. Wait until you accelerate to your endurance pace before calculating your walking speed.
Time how many minutes it takes you to walk 1 mile with a stopwatch. Locate the beginning and end markers for one mile using a GPS system or a traditional map. Divide 60 by your single-mile time to determine your mile-per-hour pace. For example, if it took 30 minutes to walk 1 mile, then you are walking at a speed of 2 mph. A 20-minute mile would equate to 3 mph.
Walk one full lap around a standard track while timing yourself. One lap at a standard track equals 1/4 mile. Multiply the time by four to determine your walking speed. For example, a five-minute lap would mean that you are walking a 20-minute mile, or walking at 3 mph.
Move your workout to a treadmill, which can track both the time and length of your workout. Remain on the treadmill until you reach your distance goal, such as 3 miles. Notice the time it took to complete your workout. Divide that time by the number of miles walked to determine the per-mile pace. Three miles walked in 60 minutes would mean a speed of 3 mph.
Download a smartphone app to easily track the distance and speed of your walk. Apps that work with numerous popular smartphone operating systems can map your walk, keep track of your step count, time your workout and estimate your calorie burn. Review the features on each app to pick the one that best fits with your workout needs.