A method of measuring a thickness of mailpieces includes calculating, for each mailpiece comprising a unique collation, an estimated mailpiece thickness value, including combining a measured envelope thickness value, a measured insert thickness value for each insert associated with the mailpiece, and a theoretical document thickness value for an input document associated with the mailpiece. The method further includes assembling the mailpiece, obtaining a measured mailpiece thickness value for the mailpiece, and comparing the measured mailpiece thickness value with the estimated mailpiece thickness value. The method further includes, where the measured mailpiece thickness value is within a predetermined tolerance of the estimated mailpiece thickness value, storing the measured mailpiece thickness value as a reference thickness value in a database on a processing device, and where the measured mailpiece thickness value is outside of a predetermined tolerance of the estimated mailpiece thickness value, outsorting the mailpiece.