On average, it takes about 2 hours 40 minutes to run 16 miles. The fastest time to run 16 miles is around 1 hour 20 minutes, while the slowest is 4+ hours.
For an average runner, the time to run 12 miles is around 2.5 to 3 hours. For some seasoned runners, a good time for 12 miles is within 1.5 to 2 hours.
The time to run 2.5 miles depends on your fitness level but typically ranges from 20 to 30 minutes for experienced runners and 30 to 40 min for beginners.