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05.10 How to Use Architectural and Engineering Scales

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Architectural Scale

An architectural scale is a specialized ruler that is used to measure and draw objects at different scales. To use an architectural scale, first identify the scale of the drawing you are working with. This is usually indicated in the title block of the drawing. Once you know the scale, select the appropriate side of the architectural scale.

To measure a distance on the drawing, place the zero mark of the scale at the beginning of the distance you want to measure. Then, read the number on the scale that aligns with the end of the distance.

To draw a distance on the drawing, place the zero mark of the scale at the beginning of the distance you want to draw. Then, mark the desired length on the drawing using a pencil or other drafting tool.

Architectural Scale Example

Suppose you are working with a drawing that has a scale of 1/4 inch equals 1 foot. You want to measure the length of a wall on the drawing. The wall is 4 inches long on the drawing.

To measure the length of the wall, place the zero mark of the scale at the beginning of the wall on the drawing. Then, read the number on the scale that aligns with the end of the wall. In this case, the number 16 is aligned with the end of the wall. Therefore, the wall is 16 feet long in real life.

To draw a wall that is 16 feet long on the drawing, place the zero mark of the scale at the beginning of the wall on the drawing. Then, mark the 16-inch mark on the drawing using a pencil or other drafting tool.

Architectural Scale Dimensional Relationships 1

  • 3/32 = 1 foot
  • 3/16 = 1 foot
  • 1/8 = 1 foot
  • 1/4 = 1 foot
  • 3/8 = 1 foot
  • 1/2 = 1 foot
  • 3/4 = 1 foot
  • 1 inch = 1 foot
  • 1 1/2 inches = 1 foot

Engineering Scale

An engineer’s scale is a specialized ruler with six sides, each with a different scale. This allows engineers and other professionals to measure and draw objects and structures at different sizes.

To use an engineer’s scale, first identify the scale of the drawing or map you are working with. This is usually printed on the drawing. Once you know the scale, select the appropriate side of the engineer’s scale. For example, if the scale of the drawing is 1 inch = 20 feet, you would use the 1:20 side of the scale.

To measure a distance on the drawing, simply place the engineer’s scale along the distance, with the zero mark at one end. The number at the other end of the distance is the measurement in feet.

Engineering Scale Example

For example, if you measure a distance of 2.5 inches on the drawing using the 1:20 scale, the actual distance would be 50 feet (2.5 inches 20 feet/inch).

You can also use an engineer’s scale to draw objects and structures at different scales. To do this, simply place the engineer’s scale along the desired dimension of the object or structure, and mark the desired length on the drawing.

For example, if you want to draw a wall that is 20 feet long on a drawing with a scale of 1 inch = 10 feet, you would place the 1:10 side of the engineer’s scale along the desired length of the wall and mark the 2 inch mark on the drawing.

Engineering Scale Dimensional Relationships

  • 1 inch = 10 feet
  • 1 inch = 20 feet
  • 1 inch = 30 feet
  • 1 inch = 40 feet
  • 1 inch = 50 feet
  • 1 inch = 60 feet

  1. Using Engineer and Architectural Scales - US Fire Administration external link (Archive)  ↩︎