Driving distance from San Diego, CA to Tijuana, Mexico. The total driving distance from San Diego, CA to Tijuana, Mexico is 18 miles or 29 kilometers. Your trip begins in San Diego, California. It ends in Tijuana, Mexico. If you are planning a road trip, you might also want to calculate the total driving time from San Diego, CA to Tijuana, Mexico so you can see when you'll arrive at your destination.