A new method for analysing the internal strain in thrust sheets is described. The displacement-distance diagram can be used to quantify the relative shortening (or relative stretch) between the hangingwall and footwall beds of a thrust and is a useful way of analysing commonly occurring fold-thrust structures. The stretch is a function of the relative rates of thrust propagation and thrust slip. The cumulative displacement-distance diagram described here can be used to calculate the absolute shortening or extension, when this is accommodated above a single décollement in a linked-fault system. This method offers a useful way of analysing duplex structures and large-scale, foreland thrust zones, as well as extensional fault systems and can be used as an alternative to, or in conjunction with, balanced cross-sections. Both methods can be used to quantify the variation in shortening above a single detachment zone; this variation may be mechanically significant, reflecting lithological control on thrust or normal fault growth.