Born and perfected in Australia, the elite selection of F45 Workouts combines elements of high-intensity interval training (HIIT), circuit training, and functional training. We’re big fans of real, noticeable changes in quick succession. That’s where 45 comes in. In just 45 minutes, F45 members can burn 400-600 calories, delivering the amazing, post-workout euphoria, all in under one hour. Workout at your own pace.