Present disclosure provides a method including isolating DNA from a source, thereby providing a composition including the isolated DNA. The isolated DNA has at least first and second target regions, where the length of the second target region is greater than the length of the first target region. The method further includes quantifying a total mass of the isolated DNA, quantifying a first quantification cycle (Cq) of the first target region and a second Cq of the second target region, and calculating a Q-ratio for the isolated DNA by dividing the second Cq by the first Cq. The method further includes determining a value for a quality-mass constant (kQm), estimating a required input mass by dividing kQm by the Q-ratio, and preparing the isolated DNA for sequencing if the total mass of the isolated DNA in the composition is equal or greater than the required input mass.