>>40643425
They're just not comparable, 4mg of pills are not the same as 4mg of gel or injections or patches. Even the same pills will get absorbed very differently based on whether they are taken orally or sublingually, and gel will be absorbed worse or better based on the area of the body it is applied to for example. Different administration methods with different ways of entering the body will each have unique absorption. Not even different injection or pill esters are completely comparable between each other, the same dose of valerate and enanthate injections will give you different levels for example even disregarding the half life (see image), and also 2mg of EV pills is equivalent to about 1.5mg hemihydrate.

4mg is a pretty standard EV dose and should put most people at over 200pg/ml at trough and lead to adequate T suppression.
You can use this calculator to play around with different doses https://transfemscience.org/misc/injectable-e2-simulator/