Why don't we consider the reduce cross-sectional area while calculating stress in a metallic wire?

Consider a wire which is being pulled by a force (within elastic limit) then the reaction force will be equal to the applied force then we say that the stress will be equal to applied force/cross-sectional area but at the same time we also know that there will be a decrease in the cross sectional area then why don't we consider it while calculating stress ?

• How much is the area reduced? If the reduction is small, then it does not matter much for the calculation. If it is significant, then the increased stress will make the problem nonlinear. – Anders Sandberg Dec 15 '19 at 12:27