Proportional calipers are commonly used when working from a live model to scale down to a smaller-than-life sculpture, but they can just as easily be used to scale up a model. They offer fixed ratio settings, including 1:1, 1.5:1, 2:1, 3:1, and 4:1. The calipers can be used in two configurations: Standard configuration (outside measurements): This is the most common method. The larger curved end is used to measure the original (e.g., life-size) model, while the smaller curved end provides the scaled measurement based on the selected ratio.