Reading an architecture ruler is easy once you understand why it looks different from a standard ruler. Architects are used to working from drawings or blueprints that are reduced in scale. In other words, one foot in reality is reduced to 1/4 inches in order to make the image fit on the page. An architect, then, turns to the 1/4-inch calibrated portion of his ruler to determine the actual measurement.
Lay out the blueprint or drawing that you want to read with the architectural ruler.
Locate the scale on the drawing or blueprint. This is typically found on the bottom left-hand side of the page.
Locate the corresponding scale on the architectural ruler, i.e. 1/4" = 1' (1/4 inch = 1 foot).
Align the edge of the ruler (using the side with the "1/4" marking at the end) alongside what you want to measure.
Place the zero at the beginning of what you want to measure and write down the final measurement. You will see that the "2" on the 1/4" ruler means two feet in actual measurement, but on paper is only equivalent to 1/2," or 2 x 1/4."