Scale is defined as the ratio of the length of any object on a model (blueprint) to the actual length of the same object in the real world. When we draw a real-world object on a piece of paper, we use a scale to describe our measurements accurately.

Scale is how we describe the size of the model as a fraction or ratio compared to the full-size subject. If you build a full-size replica, as a group in Russia recently did of the Razor Crest spaceship from The Mandalorian, it is a 1/1 (1:1) scale model.

The scale size of a model is a fraction of the real size. A 1:18 scale model is 1/18th the size of the real vehicle. The smaller the number in the scale size, the larger the model. As an example, if you have a 12 foot long vehicle, then the model size at scale would be:

Making a measurement smaller or larger, known as scale conversion, requires a common scale factor, which you can use to multiply or divide all measurements. To scale a measurement down to a smaller value, for instance, when making a blueprint, simply divide the real measurement by the scale factor.