|This running calculator uses the distance and finish time of a recent race to approximate your current level of fitness. Your performance is the result of many factors, including the maximum rate at which your body can process oxygen, your lactate threshold, and the mechanical efficiency of your stride. The calculator lumps the effects of all these factors into a single variable called VDOT, using a method popularized by sports scientist Jack Daniels in his book Daniels' Running Formula.
A given VDOT value corresponds to successively slower average paces as race distance increases. For example, VDOT 40.0 represents a 7:45/mile pace for a 5K race (24:05 total time), but 8:02/mile pace (49:58 total time) for a 10K, with both performances indicating the same overall level of fitness. Once your current VDOT has been determined, it can be used to predict your race times at other distances. The closer the other distance is to the original race's distance, the more accurate the prediction will be. Due to differences in physiology and training, some people may be better at longer distance races than shorter ones or vice-versa, but the calculator should yield accurate results for most runners.
The recommended training paces are also determined from your current VDOT value. They correspond to the five primary training types as defined by Daniels: everyday easy runs, marathon pace runs, tempo (lactate threshold) runs, intervals, and repetitions. These training types and the purposes served by each are explained fully in Daniels' book.
At Dr. Daniels' request, the custom Runworks calculator that was previously here has been replaced with an embedded version of his official calculator, developed by the Run S.M.A.R.T. Project.