Setting Up a Drawing - AutoCAD 2011 and AutoCAD LT 2011: No Experience Required - page 95

The tools covered in this chapter are your keys to starting a new drawing from
scratch and getting it ready for a specific project.
A Summary of AutoCAD's units
The following is a brief description of each of the linear and angular unit types
that AutoCAD offers and how they are used. The example distance is 2 ′ -6½ ″ . The
example angle is 126°35 ′ 10 ″ .
Linear units
The linear unit types that AutoCAD uses are as follows:
Architectural This unit type uses feet and inches with fractions. You must use
the foot sign ( ′ ): for example, 2 ′ -6½ ″ . For this distance, enter 2'6-1/2 or 2'6.5 .
For the most part, these are the units that you'll use in this topic.
Decimal This unit type uses Decimal units that can represent any linear unit
of measurement. You don't use the foot sign, the inch sign, or fractions. This
method is especially common in the civil engineering discipline where Decimal
units are used, and 1 unit is equal to 1 foot. Therefore, for the distance 2 ′ 6½ ″
you would need to convert the inches (6.5 inches in this case) to the decimal
equivalent of a foot (6.5/12 = .5417). So in this case, you would enter 2.5417 .
Let's say you needed to draw a line 10 ′ 3 ″ long in a drawing where 1 unit was
equal to 1 foot. You would need to convert the inches to the decimal equivalent
of a foot. So in this case 3/12 = .25, and so you would enter 10.25 .
Conversely, if each unit was equal to an inch, that same 2 ′ 6½ ″ line would be
entered as 30.5 (2 × 12) + 6 = 30 and 6/12 = .5.
Engineering This unit is equivalent to Architectural units except that inches
are displayed as decimals rather than fractions. For a distance of 2 ′ -6½ ″ , enter
2 ′ 6.5 or 2.5417 ′ . In either method, the resulting distance is displayed as 2 ′ -6.5 ″ .
Fractional These units are just like Architectural units except there is no use of
feet. Everything is expressed in inches and fractions. If you enter 30-1/ 2 or 30.5 ,
the resulting distance displays as 30½.
Scientific This unit system is similar to the Decimal unit system except for the
way in which distances are displayed. If you enter 3.05E+ 01 , that is what is dis-
played. The notation always uses an expression that indicates a number from 1
to 10 that is to be multiplied by a power of 10. In this case, the power is 1, so the
notation means 3.05 × 10, or 30.5 in Decimal units.