Convert from kerat to palm [Britain, Roman minor]

Unit Definition (kerat)
The kerat is a traditional Middle Eastern unit of length, equal to about 9/8 inch or 2.86 centimeters. The unit has the same Arabic root as the carat or karat.

Unit Definition (palm [Britain, Roman minor])
A palm, when used as a unit of length, is usually four digits or three inches, i.e. 7.62 cm (for the international inch). The width of an adult human male palm is indeed about 10 centimetres.In English this unit has mostly fallen out of use, as do others based on the human arm: digit (¼ palm), finger (7/24 palm), hand (4/3 palms), shaftment (2 palms), span (3 palms), cubit (6 palms) and ell (15 palms).