We determine optimal electrode shape and size of lateral-field-excited (LFE) thickness-shear resonators. The determined electrodes are optimal in that they satisfy the criterion for Bechmann's number in every direction. Numerical and graphical results are provided for AT-cut quartz, (yxl)- 45°langasite, and (yxl)-16.5°LiTaO(3) LFE resonators. The optimal electrodes of AT-cut quartz LFE resonators are also compared with those of AT-cut quartz thickness-field-excited (TFE) resonators.