Method and apparatus for trimming a magnetic field sensor having a first magnetic field sensing element. In embodiments, trimming includes the use of a curve for normalized sensitivity of the first magnetic field sensing element derived from a first curve corresponding to current through a coil in a first direction at a first time to produce a field affecting the first magnetic field sensing element versus an external field and a second curve corresponding to current through the coil in a second direction opposite to the first direction at a second time to produce a field affecting the first magnetic field sensing element versus an external field.