The first thing a runner needs to do to create a training plan for a half marathon is determine his current running level. Training plans for first-time marathoners entail a much less strenuous schedule than training plans for runners who want to finish the course in 90 minutes or under, for example. For the former, a training plan involves 10 weeks of training, running 9 to 24 miles every week, with three days of rest or cross-training.
From this lower level, training plans become more intense the higher the level of the runner. For example, an intermediate level training schedule suits a runner who has some experience in these kinds of races and has a few years under his belt as a serious runner. This training plan involves between 25 and 30 miles of running every week leading up to the half marathon.
Moving up from this level to even more experienced runners, or those who have run strong half marathons before and are shooting for a specific time, the mileage per week goes up depending on the schedule. It can involve between 42 and 50 miles a week and six days of running. Some plans also call for an extended schedule before the race in which the runner trains for 14 weeks instead of 10.