To run a marathon in under four hours, you need to sustain an average pace of at least 6.55 miles/hr for 26.2 miles. This is equivalent to a pace of 9 minutes and 9 seconds per mile or 5 minutes and 41 seconds per kilometer. Running a marathon in under four hours is considered a good goal for many runners, and it shows not just endurance but also a good level of underlying fitness and training behind it. To achieve this goal, you need to train yourself to run a consistent pace for four hours, factoring in any challenges such as big hill sections or other obstacles. A successful 4-hour marathon is all about pacing, and your pacing strategy can be broken into two elements: speed and consistency. To break 4:00, you should eventually be capable of a sub-1:50 half-marathon (8:20 per mile) and sub-50:00 10K (8:00 per mile) .