Which statement correctly defines nominal size in engineering drawings?

• A. The measured size from a particular piece
• B. The intended dimension the part is designed for
• C. The maximum allowable size
• D. The minimum allowable size

Answer: (B)

Nominal size is the intended dimension the part is designed for. It’s the target value shown on the drawing that you use as the reference when setting tolerances. The actual size of a manufactured piece can vary, but must stay within the allowed range defined by those tolerances. The maximum and minimum sizes specify that range, not the target value. For example, a nominal size of 50 mm with a tolerance of ±0.1 mm means the part is designed to be 50 mm, but it may be produced anywhere from 49.9 mm to 50.1 mm.