Performance tools compare an effort with a published standard or with another clock. The running performance calculator puts age grading, VDOT, equivalents, training paces, and heart-rate zones on one screen from a recent race. Grade-adjusted pace estimates what a hilly split would have been on the flat, using Minetti’s 2002 energy-cost polynomial. Age grading compares a 5K, 10K, half marathon, or marathon with interpolated World Masters Athletics 2015 factors. Reverse grading starts from a target percent. Cooper 1968 and VDOT estimate VO2 from a field test or a race.
Neither GAP nor age grade is a GPS measurement, an official ranking, or a qualifying standard. Cooper and VDOT are field estimates, not a metabolic cart. Race comparison uses VDOT; PB improvement is exact arithmetic on the same distance. The flat sea-level marathon equivalent calculator strips altitude and hills, then shows equal-weight VDOT and Riegel marathon clocks (and can compare two course-adjusted races). Marathon potential and goal feasibility use Riegel and say so.
Use them to interpret a result, then apply judgement. For even splits or race prediction, open the races category. Track intervals live under Track. Formulas and citations are on the methodology page.