58 Chapter 4
length of the instrument: one is read from left to right and the other from right to left. Likewise, a scale
is usually either half or double that of the scale it is paired with. For example, if one end is a 1/8-inch
scale, the opposite end is a 1/4-inch scale; the opposite end of a 1 1/2-inch scale would be a 3-inch
scale.
The scales are designed to measure feet, inches, and fractions of an inch. Below are the most com-
mon scales found on the triangular architect’s scale with their approximate metric equivalent in paren-
theses:
- 1/32 inch = 1 foot (1/400 metric equivalent—often used for site plans—actual 1/384)
- 1/16 inch = 1 foot (1/200 metric equivalent—often used for large projects and small site plans—
actual 1/192) - 1/8 inch = 1 foot (1/100 metric equivalent—actual 1/96)
- 1/4 inch = 1 foot (1/50 metric equivalent—actual 1/48)
Figure 4.3 A drawing with examples of diametral and radial dimensions.