The average 5k run time depends on the level of experience of the runner. If someone just starting out runs a 12-minute mile, he will complete the race, which is roughly 3.1 miles, in about 37 minutes. If a more experienced runner runs a 9-minute mile, he will finish the race in about 28 minutes.
The average time for a 5k depends primarily on experience level, but other factors such as road conditions, hills, temperature, a crowded field of competition and proper hydration and nutrition also factor into a 5k race time. It is important for a runner to keep track of his own practice run times in order to discover an average for the 5k race day.