Find out the distance, in miles, you will be traveling round trip. Refer to an atlas, road map or Google Maps. To search on Google Maps, type in the address of your starting and ending locations under the Directions tab. Scroll down to the bottom past the directions until you find the travel distance. Multiply that number by two for the round-trip distance.
Calculate the average speed you will travel in miles per hour. A Global Positioning Satellite unit (GPS) can calculate the average speed. You will need to search for the appropriate tool within your own GPS and reset it before your trip to get a better measurement.
Log your break times. If you are taking a long trip, you will need time to stop for bathroom breaks, refueling and meals. Once you have logged all your break times, add them together and convert your minutes into hours by dividing the total time by 60. For example, if you took an accumulated break time of 30 minutes, your equation would be:
30 minutes / 60 = 0.5 hours
Plug the values from Steps 1 to 3 into the following equation: Time = (distance traveled round-trip / average speed) + total break time. For example, suppose your average speed was 65 mph, total distance traveled was 500 miles and total break time equaled 0.5 hours:
Time = (500 miles / 65 mph) + 0.5 hours = approximately 8.19 hours
