# How to Calculate Blueprints With an Architect's Ruler

#### Things You'll Need

• Architectural scale

• Scaled architectural drawings

Architectural drawings are drafted using defined scales.

Architecture is much larger than humans and cannot be depicted on paper at true size. Instead, architects draw buildings to a scale -- one foot is equivalent to a fraction of an inch on paper. Because of this, it is difficult to understand the size of building elements on a drawing unless you have an architect's ruler (also called a scale). Each side of the scale is graduated into feet and inches. Architects, engineers and contractors can use the measurements on the scale to find true dimensions of the structure represented.

## Step 1

Unfold or unroll your architectural drawings, sometimes called blueprints. Each drawing is drawn to a scale, but the drawings might have different scales. So, it is important to look for the given scale on a drawing sheet.

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## Step 2

Look for the scale, which will be located below the drawing title or somewhere on the title block. Sometimes, a drawing will provide a drafted, graphic scale, instead of a written scale. The scales will be given as a fraction of an inch equal to one foot, such as 1/4 inch equals 1 foot. Alternatively, some drawings define the scale as "1 inch equal to a number of feet," such as "1 inch equals 32 feet."

## Step 3

Note the scale of the drawing, and look for the corresponding scale on the architectural scale. For example, a drawing with a scale of "1/8 inch equals 1 foot" will use the side of the scale that is indexed as 1/8. If 1 inch equals a certain number of feet, such as 1 inch equals 16 feet, write a fraction with the scaled dimension as the numerator and the true dimension as the denominator. Thus, "1 inch equals 16 feet" is marked as 1/16 on the scale.

## Step 4

Use the side of the architectural scale that corresponds to the drawing's scale. Each tick on the scale is equivalent to 1 foot, and some scales provide scaled inches on the opposite side of the zero mark. Be careful to use the correct indexed numbers -- to save space, most architectural scales will use one set of tick marks for two scales. For example, most scales pair "1/4 inch equals 1 foot" with "1/8 inch equals 1 foot," although "1/4 inch equals 1 foot" is two times larger than "1/8 inch equals 1 foot." Furthermore, "3/32 inch equals 1 foot" is usually paired with "3/16 inch equals 1 foot."