The goal of this study was to develop a method to analyse the seat-belt force-time history measurements obtained from laboratory crash tests to characterise the b pre-tensioner and load-limiting features. The study also aimed to describe how these characteristics have changed over the past 40 years using NHTSA’s crash test database. The method was used to identify the pre-tensioner time-to-fire (TTF) and force level, and load-limiter force by analysing the shape of the force-time history curves measured at the lap and shoulder belts in laboratory crash tests. The method was applied to the full-width frontal crash tests at 56 km/h of the New Car Assessment Program (NCAP), gathered from the NHTSA vehicle crash test database from the last 40 years. The algorithm’s accuracy in identifying the presence of a pre-tensioner and load limiter was 90% and 89%, respectively. The adoption of both devices started in the mid-1990s, and they were widely adopted in most tested vehicles by 2005. The study provides ranges for the TTF and force of the pre-tensioner and load-limiter force for different configurations of the seat-belt system. The algorithm was successfully developed and validated, making it useful for future injury risk studies.