Performance factor is a rough way of measuring how well you run over different
distances. For any distance a PF of 1000 aproximately corresponds to a
 world record. A PF of 600 is closer to High School performances

formula for performance factor pf = (3337/pace)*(kilom^.0689) where pace is in minutes per mile kilom is total number of kilometers run. An attempt at an explanation of the formula: The equation (3337/pace) for the same distance goes down asymptotically toward 0 as pace increases. The equation (dist^.0689) increases exponentially (with a decreasing rate) as distance increases for the same pace. Multiplying the two functions gives the performance curve that varies with pace and distance.