This finishing time equates to an average pace of just under 3 minutes per kilometer or 4 minutes 44 seconds per mile which is an average speed of over 20.4 km per hour. For most runners however the average time for completing a marathon is 4 hours 30 minutes for men and 5 hours 10 minutes for women.The majority of recreational runners have other reasons for entering a marathon such as to achieve a lifetime goal or to raise money for a worthy cause.ne goal in particular that some runners strive to achieve is to break certain time barriers. For example, recreational first timers may plan to complete the race in under 4 hours, whilst seasoned and more experienced marathon runners could be aiming to finish in under 3 hours.