The gyromagnetic ratio, often denoted by the symbol γ (gamma) is the ratio of the magnetic momentum in a particle to its angular momentum.
The SI unit is the radian per second per tesla (rad⋅s−1⋅T−1).
The gyromagnetic ratio of the proton is 2.675 221 900(18) x 108 s-1 T-1.
Since a proton will precess at a specific frequency when placed in an external magnetic field, proportional to the gyromagnetic ratio times the strength of the magnetic field over 2π, the gyromagnetic ratio is often transformed into a more useful form, denoted in units of MHz/T.
At an external field strength of 1 Tesla, the gyromagnetic ratio of the proton over 2π is 0.42577478925(286) MHz T −1.