The international standard ISO 1413 Horology--Shock-resistant watches specifies the minimum requirements and describes the corresponding testing method. It is intended to allow homologation tests rather than the individual control of all watches of a production batch. It is based on the simulation of the shock received by a watch on falling accidentally from a height of 1 m onto a horizontal hardwood surface.
In practice, shock resistance is generally tested by applying two shocks (one on the 9 o'clock side, and one on the crystal perpendicular to the face). The shock is usually delivered by a hard plastic hammer mounted on a pendulum, so as to deliver a measured amount of energy, specifically, a 3 kg hammer with an impact velocity of 4.43m/s. The watch must keep its accuracy to +/- 60 seconds/day as measured before the test.