  We compute the one-loop corrections to $Z$ decay properties from dimension-6
operators in the Standard Model Effective Field Theory (SMEFT) that contribute
also to anomalous 3-gauge boson couplings and examine the relative sensitivity
of the two processes to the anomalous couplings. The size of the contributions
is of order a few percent, of the same size as Standard Model electroweak
corrections. This is part of a program of computing electroweak quantities to
one-loop in the SMEFT: these calculations are needed for a future global fit to
limit the coefficients of the dimension-six Wilson coefficients consistently at
one loop.
