Scale Drawings and Models

Scale Drawing

A scale drawing is a proportional representation of an object. The scale is the ratio of the drawing size to the actual size.

Scale Factor

If a map has a scale of 1 cm : 50 km, then 1 cm on the map represents 50 km in reality. The scale factor is 1/5,000,000.

Finding Actual Dimensions

Set up a proportion using the scale:

drawing measurement / actual measurement = scale

Example: A blueprint has scale 1 in : 4 ft. A room measures 3.5 in on the blueprint. Actual length = 3.5 × 4 = 14 ft.

Scale Models

Three-dimensional versions of scale drawings. Same principles apply — all linear dimensions are scaled by the same factor.