Stiffness is one of the key points for research and development of vehicle body in white (BIW). Fast and effective evaluation of stiffness is very important for reducing the time and cost of research and development. How to realize weight reduction with proper stiffness is also a focus point of automobile design. In general, commercial software is used to optimize the BIW design. But the optimization process is time consuming. Therefore a simple but effective tool for fast evaluation is desired.A method to evaluate stiffness with sensitivity coefficients of sheet metal thickness of body structure is proposed in this paper. The simple mathematical relation of the sensitivity coefficients, the thickness variation of sheet metals, and the stiffness of body structure is established. The stiffness can be evaluated quickly for various combination of sheet metal thickness without running large-scale simulation using commercial software. An excel spreadsheet is also developed for fast evaluation by design engineers.Examples are presented to show the effectiveness of the proposed method.