We present an analytical model for the calibration of lateral piezoresistance stress gauges in shock‐wave experiments. This calibration is based on our experimental data with transverse Manganin gauges in shock‐loaded polymethylmethacrylate targets. The experiments included lateral stress measurements under shock loading in the 1–30‐kbar range and under complete unloading from stresses in the 5–9‐kbar range. These unloading measurements resulted in a negative resistance change for the transverse Manganin gauge which implies that a hydrodynamic tension exists in it. The validity of our analytical calibration is demonstrated by comparing measured and predicted lateral stresses in glass targets.