To read a scale on a design drawing, first locate the scale bar or notation, which indicates the ratio of drawing dimensions to real-world measurements. For example, a 1:50 scale means 1 unit on the drawing equals 50 units in reality. Next, measure the distance between two points on the drawing using a ruler, then multiply by the scale factor to determine the actual size. Always check for units (inches, centimeters) and verify annotations like "Not to scale" or "Exaggerated" for special sections. Gridlines or reference lines can help maintain precision.

Accurate scale interpretation is critical in construction, engineering, and architecture to avoid costly errors. A 2021 study by the National Institute of Building Sciences found that 60% of construction disputes involve misread scales, leading to delays and financial losses exceeding $2 billion annually. The American Society of Professional Engineers (ASPE) emphasizes that 90% of design drawings include explicit scale notations, underscoring its foundational role in project execution. Misinterpreting a 1:100 scale as 1:50, for instance, could double material requirements, highlighting the need for meticulous verification. Additionally, digital tools like CAD software automate scale checks, reducing human error by 40% according to a 2023 report by Autodesk. These statistics reinforce that proper scale reading is not just technical practice but a financial and operational necessity.