An architect’s scale is also known as the scale rule. It helps the architect quickly interpret the dimensions of a blueprint without having to wrack his brains on math. The architect’s scale looks odd with three sides, having a different ruler on every side. You can read fractions of an inch like ½ or ¼ in the architect’s scale.

First or all, find the scale on your blueprints. You will find it located on the bottom left hand corner of the page. For instance, ¼" can be interpreted as 1 ft. When you have done this, find the corresponding scale, on the ruler. The scale has a long mark to the left of a ‘0’ which is the starting part of the feet, and many shorter marks to the right part of the ‘0,’ which signify the inches. Align the ruler straight with the zero mark on the beginning of the part you want to measure. The foot measurement is the closest mark the line passes. Having counted the feet, move the ruler left to match the end of the line with the closest foot mark. The smaller ‘inch’ mark that the line meets up with is the inches that you need. The first measurement is an indication of the feet, and the second shows the inches.