The base pair size of the excess DNA in the smallest three partial digestion bands for the variable number of tandem repeat loci D1S7, D2S44, D4S139, D5S110, D10S28, and D17S26 has been quantitatively evaluated using data obtained from intentional partial digestion of liquid blood DNA. Restriction fragment length polymorphism (RFLP) measurement characteristics specific to the performing laboratory were evaluated from that laboratory's historical K562 cell line control data. The expected size of the excess DNA is estimated as the weighted mean of the differences between the measured size of the partially digested bands and the fully digested band, with the weights predicted using knowledge of RFLP measurement characteristics. Confidence limits are developed for evaluating whether the size differences among a set of RFLP band multiplex observed in pristine samples are consistent with those expected from partial digestion. The base pair size of excess DNA for partials observed in evidentiary samples appears to be somewhat less than that from pristine samples. Tables, figures, references