# Why is the standard model renormalizable if we believe it is an effective theory? [duplicate]

We believe that the standard model is only an effective field theory of its true UV completion. However, effective theories have dimensionful couplings and are not renormalizable. The standard model has dimensionless couplings and is renormalizable. So then how is the standard model both an effective theory but also renormalizable?

Edit: Is this the answer: if we have a theory with dimensionless couplings, then look at it on a lower energy scale, it will look like an effective theory with dimensionful couplings. But a "grand unified theory" won't have dimensionless couplings. It will have dimensionful couplings, perhaps with the size of the planck mass. So while the standard model might be an "effective theory" of the "grand unified theory," it has dimensionless couplings instead of dimensionful couplings, because the "grand unified theory" already had dimensionless couplings that are irrelevant at our scale.