Uncia (unit)

The uncia (plural: unciae) was a Roman unit of length, weight, and volume. It survived as the Byzantine liquid ounce (Greek: ουγγία, oungía) and the origin of the English inch, ounce, and liquid ounce.

The Roman inch was equal to  ¹⁄₁₂ of a Roman foot (pes), which was standardized under Agrippa to about 0.97 inches or 24.6 millimeters.

The Roman ounce was  ¹⁄₁₂ of a Roman pound.