How to Use an Architectural Scale Ruler

Look for the scale. Whether you have a flat or a multi-sided architectural scale ruler, the scale will be clearly marked at each end of the ruler.

Make sure that you have the appropriate scale for the job you are doing. For example, if you are drawing a floor plan at a ¼ scale, then you need to have the ¼ scale on the architectural scale ruler.

Draw a straight line on a blank piece of paper using a straight edge, such as a T-square and a light pencil. If you are measuring the lines on a pre-made floor plan, then skip this step.

Align the architectural scale ruler to the straight line.

Measure out the appropriate length based on the scale you are using. If you are drawing a new set of floor plans, for example, use a light pencil to mark the desired length. If you have a premade floor plan that you are measuring, write the measurement down on a piece of paper.

Darken the line within the space marked off with a dark pencil. If you have a pre-made floor plan, skip this step.