In high-k/metal-gate metal-oxide-semiconductor field-effect transistor (MOSFETs) at 45-nm and below, there is a problem that the metal-gate material consists of a number of the grains with different grain orientations and probability values. In order to estimate the work-function-variation-induced (WFV-induced) threshold voltage (V<SUB>TH</SUB>) variation, the Monte Carlo simulation can be used, but it requires the statistically-significant number of samples more then 10<SUP>6</SUP>. In this work, we suggested a simple matrix-model. The suggested model has beenverified with the experimental data, and we discussed the amount of the WFV-induced VTH variation.