Nails aren't called "D" in the way the question implies. The "d" in nail sizing, such as 8d or 16d, actually stands for penny. This historical designation refers to the cost of a specific quantity of nails, with a larger penny number indicating a longer and thus more expensive nail. It's a way to indirectly specify the nail's length.
Understanding the "Penny" System
The "penny" system for nail sizing is a legacy system; the "d" is an abbreviation for "penny". It doesn't represent a modern metric of size like length in millimeters or inches, although there's a rough correlation. For example:
- 8d nail: This is a relatively short nail.
- 16d nail: A significantly longer nail than an 8d.
- Larger penny numbers (e.g., 20d, 30d): Represent even longer nails.
While the precise length varies slightly depending on the manufacturer, the penny system provides a general indication of nail size based on its historical cost and resulting length. This system is less common now, with modern sizing more frequently using inches or millimeters.
