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CAD Scale Factors

For simplicity and clarity, CAD users draw buildings at full scale.  For instance, when drawing a door in CAD, the door would be 3 feet wide and 7 feet tall.  However, since these drawings get placed on sheets of paper that are much smaller, a scale factor is required so that the final drawing has a usable conversion factor.

Calculating Scale Factor

To convert an architectural drawing scale to a scale factor:

  1. Select the desired scale.  1/8" = 1'-0"
  2. Invert the fraction and multiply by 12. 8/1 x 12 = Scale Factor 96

To convert an engineering drawing scale to a scale factor:

  1. Select the desired scale. 1" = 20'
  2. Multiply the feet by 12.  20 x 12 = Scale Factor 240 

Architectural Scales

 Drawing Scale
Scale Factor
Viewport Scale
Decimal Scale
 1/16" = 1'-0"
192
1/192xp
.0625" = 1'-0"
3/32" = 1'-0"
128
1/128xp
.09375" = 1'-0"
1/8" = 1'-0"
96
1/96xp
.125" = 1'-0"
3/16" = 1'-0"
64
1/64xp
.1875" = 1'-0"
 1/4" = 1'-0"
48
1/48xp
.25" = 1'-0"
 3/8" = 1'-0"
32
1/32xp
.375" = 1'-0"
1/2" = 1'-0"
24
1/24xp
.50" = 1'-0"
3/4" = 1'-0"
16
1/16xp
.75" = 1'-0"
1" = 1'-0"
12
1/12xp
1" = 1'-0"
1 1/2" = 1'-0"
8
1/8xp
1.5" = 1'-0"
3" = 1'-0"
4
1/4xp
 3" = 1'-0"

Engineering Scales

 Drawing Scale
Scale Factor
Viewport Scale
1" = 10'-0"
120
1/120xp
1" = 20'-0"
240
1/240xp
1" = 30'-0"360
1/360xp
1" = 40'-0"
480
1/480xp
1" = 50'-0"
600
1/600xp
1"= 60'-0"
720
1/720xp
1" = 70'-0"840
1/840xp
1" = 80'-0"
960
1/960xp
1" = 90'-0"
1080
1/1080xp
1" = 100'-0"
1200
1/1200xp



 


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