Duodecimal

Proceeding in computation by twelves; expressed in the scale of twelves.

A twelfth part; as, the duodecimals of an inch.

A system of numbers, whose denominations rise in a scale of twelves, as of feet and inches. The system is used chiefly by artificers in computing the superficial and solid contents of their work.

one part in twelve equal parts

based on twelve; "the duodecimal number system"