Predicting your marathon finish time is useful for setting pacing strategy, training targets and race expectations. One of the most common mistakes runners make is setting a marathon goal time that is not based on current fitness. A common way to estimate marathon performance is to use a recent race result, such as a 5 km, 10 km or half marathon, and apply an endurance prediction formula. These formulas assume that performance declines at a predictable rate as distance increa