Boeing Stabilizer Trim
Boeing's convension for stabilizer trim is that a degree of stabilizer is equal to one unit of pitch trim as displayed to the flight deck crew. The range of motion for the stabilizer on Boeing commercial jets is approximately 15 degrees. Pilot pitch trim units are 0 for most airplane nose down and about 15 for most airplane nose up.
Note that stabilizer position is positive in the trailing edge down direction that causes nose down pitching moment - this polarity is opposite that displayed to the flight deck crew. Also note that the zero stabilizer position corresponds to alignment with the fuselage. Typically the stabilizer range of travel is from about +4 deg (most trailing edge down) to about -11 deg (most trailing edge up). For simplification, the pitch trim range shown to the flight deck crew has positive values only.