Years of potential life lost (YPLL)/Potential years of life lost (PYLL) An estimate of the average years a person would have lived if he or she had not died prematurely. It is a measure of premature moality/death. Deaths occurring in individuals age 75 or older are NOT included in the calculation. For YPLL calculation, Numerator is years of potential life lost. denominator is the population under 75 years of age. - It is based on the years of life lost through premature death.