PurposeTo analyze the changes in craniofacial morphology during speaking and wearing masks using three-dimensional head data and to develop a design method for ergonomic face shields.Design/methodology/approachAround six types of face postures for three-dimensional measurement were selected; a total of 180 head data of 40 men in their 20s and 30s were used. About 17 landmarks and 23 body dimensions were measured for analysis.FindingsAmong the 23 anthropometric dimensions, eight in posture “a,” two in posture “i,” seven in posture “u,” ten in KF94 and ten in N95 were found to change significantly. Previous studies and public health recommendations selected three key dimensions for face shield design. A face shield design method using selected dimensions as parameters was developed.Social implicationsTo improve public health and enhance social interaction during pandemics or in environments requiring facial protection. This can lead to increased compliance with public health guidelines and reduce discomfort and communication barriers caused by ill-fitting face shields.Originality/valueBy developing an ergonomic face shield design that accommodates variations in craniofacial morphology during speaking and mask, the study addresses the need for more comfortable and effective protective equipment. The face shield designed using the methodology developed in this study was verified on a digital head model to demonstrate a good fit.