MAST Upgrade has just begun its third physics campaign in April of 2023. The set of magnetic probes used to diagnose the magnetic field and currents on MAST Upgrade are described, and their calibration procedures are outlined including calculation of uncertainties. The median uncertainty in the calibration factors of the flux loops and pickup coils are calculated as 1.7% and 6.3%. The arrays of installed instability diagnostics are described, and the detection and diagnosis of a specimen MHD mode are demonstrated. Plans for the improvement of the magnetics arrays are outlined.