Metrication in Australia took place between 1970 and 1988. Before then, Australia mostly used the imperial system for measurement, which the Australian colonies had inherited from the United Kingdom. Most of the world uses the metric system, although the UK, US, and some of Canada still chose to use the imperial system of inches and feet. Our rulers are available in both systems (we'd never rule out one or the other), just speak to one of our sales team.