Disclosed embodiments relate to a method for calibrating a coordinate system of a multi-axis deceleration sensor in a rail vehicle, including calibrating the vertical axis of the sensor to the vertical axis of the vehicle, measuring the acceleration along the longitudinal and transverse axis of the sensor during a braking process of the rail vehicle at a low speed and at a standstill over a time curve, determining an offset vector at a standstill, the offset vector consisting partly of a component in the longitudinal direction and partly of a component in the transverse direction of the sensor and representing the influence of the gravitational acceleration on the measured acceleration of the rail vehicle, and ascertaining at least one resulting acceleration vector of the coordinate system of the sensor about the vertical axis of the sensor such that the at least one resulting acceleration vector faces the vehicle longitudinal direction.