Gilbert is the CGS system unit of magneto-motive force. The equivalent SI unit is Ampere-turn, and 1 Gilbert = 10/4π or 0.7958 Ampere-turns. When measuring the operate AT of a reed switch using a simply power supply and a coil, it is easy to calculate the operate AT by just noting the operate current and multiplying it with the number of turns in the test coil.
The gilbert (symbol: Gb) is an obsolete unit used in practical cgs and CGS-EMU systems to measure magnetomotive force. The unit is named for English physicist William Gilbert.
Conversion to the corresponding quantity in the SI, with the unit ampere-turn: