Architects use a triangle scale to make their drawings. The triangle scale is the one most often used because it gives the architect the ability to use a variety of scales in one instrument. There are typically 11 scales on a single triangle scale, plus an ordinary 12-inch ruler. The scaled rulers are used to draw building plans and for checking the dimensions when a building is under construction. Architects use the scale to measure out and draw the lengths of walls, doors and windows on paper in a way that will represent the building's real-life proportions.
- Find the edge of the ruler that has the 1/4-inch designation on it. On the 1/4-inch scale, increments of 4 feet are equal to 1 inch. Most floor plans are drawn at 1/4-inch or 1/8-inch scale depending on the overall size of the building and the size of the sheet. A typical set of blueprints is done on 24- by 36-inch sheets or 30 - by 40-inch sheets.
- Place the 1/4-inch scale on the piece of paper that has the floor plan you want to measure. Start with one wall on the outside perimeter, making sure to measure the outside line of the wall.
- Align the "0" mark on the 1/4-inch scale with one end of the wall you are measuring. The numbers that correspond to the 1/4-inch scale are in increments of 2 feet.
- Find the end of the wall you are measuring. Read the number on the 1/4-inch scale that is closest to the end of the wall. If the end of the wall does not exactly line up with a number on the 1/4-inch scale you will need to move the scale to the nearest whole number less than the wall length because that means the remainder of the measurement will be in inches. The number that you read at the end of the scale is your total measurement in feet for the wall you are measuring. Write this number down.
- Go back to the end of the wall where you started measuring. You will notice the "0" mark does not align with the end of the wall anymore because you moved the scale on the other end of the wall to align with a whole number on the scale. You will now need to measure from the "0" mark to where the wall ends to measure the length in inches for the total wall measurement. The longer tick marks are in increments of 3 inches. Count the number of tick marks from "0" to end of the wall and you will have your inch measurement calculated. Write this number down next to the feet measurement you wrote down earlier and you have the total scaled measurement of the wall in feet and inches.