Using a Scale Rule

Scale rules are usually white and made of plastic. They have a different scale printed along each edge. Some have a single scale per edge, and others have two scales combined on one edge.

Different brands may vary in the way the scales are grouped. A scale rule can be triangular shaped or flat, like a standard ruler.

On the top edge of the rule below, the scales are 1:1 and 1:100, so the dimensions they show differ by a factor of 100.

Another scale rule edge is shown below. In this case, the dimensions differ by a factor of 10 (1:50 is 10 times larger than 1:500).

To measure something to scale, put the zero mark on the left-hand edge of what you are measuring, and read the length at the right-hand edge, as shown below.