  The choice of an electroweak (EW) input scheme is an important component of
perturbative calculations in Standard Model Effective Field Theory (SMEFT). In
this paper we perform a systematic study of three different EW input schemes in
SMEFT, in particular those using the parameter sets $\{M_W, \, M_Z, \, G_F\}$,
$\{M_W, \, M_Z, \, \alpha\}$, or $\{\alpha, \, M_Z, \, G_F\}$. We discuss
general features and calculate decay rates of $Z$ and $W$ bosons to leptons and
Higgs decays to bottom quarks in these three schemes up to next-to-leading
order (NLO) in dimension-six SMEFT. We explore the sensitivity to Wilson
coefficients and perturbative convergence in the different schemes, and show
that while the latter point is more involved than in the Standard Model, the
dominant scheme-dependent NLO corrections are universal and can be taken into
account by a simple set of substitutions on the leading-order results. Residual
NLO corrections are then of similar size between the different input schemes,
and performing calculations in multiple schemes can give a useful handle on
theory uncertainties in SMEFT predictions and fits to data.
