The relationship between the dimensions on a scale drawing or model and the actual dimensions of the object being represented is described by a ratio. One type of ratio that could be used is called a unit scale, in which units of measure are used to relate scale dimensions to actual dimensions. For example, a unit scale for a scale drawing might be: 1 centimeter = 2 meters.

Another ratio that could be used is called a scale factor. Like a unit scale, a scale factor relates the scale dimensions to actual dimensions however it does so without regard to specific units.

A scale factor for a scale drawing might be 1200.

If you think about the unit scale that we just introduced, 1 centimeter to 2 meters, the scale factor would be 1 to 2.

Let’s look at how we can work with scale factors when given actual dimensions.